The Witcher bugs

These days, every game has bugs, whether they are major or barely noticeable. The Witcher is no different.

All bugs listed below are found to have been occurring in game version 1.3

Crash Bugs

Random crashing, often when (auto)saving
Frequent crashes have been reported by some people playing on Windows Vista. Others seem to be able to run it without crashing too often. See Technical Information for a Vista-specific tip.
Crashes continue to occur when saving or using the journal or inventory after having used ALT+TAB or CTRL+ESC frequently (usually more than ~ 5 times) during a gaming session.

Major Bugs

Shani may disappear completely if in Act II you manage to get both the Old Friend Of Mine quest to advance to "Bring Liquor" and the Anatomy of a Crime quest to advance to "Get the corpse from the Gravedigger"
Group Silver style's 4th level does not give a chance to incinerate the target(s) contrary to its description. This renders silver swords with raised incineration chance and the related Igni talent useless as they rely on Group Silver's incineration attack working.
Contrary to its description, the Quen Sign renders Geralt invincible rather than providing damage absorption based on Sign level.

Intermediate Bugs

Slain monster corpses can often obstruct the player from picking up remains, noticeable when the lever cursor is displayed but clicking has no result or the "Remains" text keeps flashing. Corpses also prevent the player from picking up dropped items nearby until they disappear. In addition, when clicking to more elsewhere, often the game makes to run exactly on top of a nearby (or even further) corpse instead, including in the opposite direction.
Even when sufficient endurance is available to cast a spell and Geralt is not otherwise hindered, at times Geralt will seem unable to cast any spells/signs (targeted at an enemy or the floor) unless he moves away a distance.
If monsters are "stuck" (either when just spawned or getting stuck in combat) they can become completely unhittable by Geralt's swords (Strong, Fast, Group) unless Geralt moves away to allow the monsters space to move or blasts them using a sign. Hitting such monsters will always result in "Dodge" being displayed.
Problem with the walkmesh in Triss' house. Sometimes Geralt can get stuck and will no longer be able to move near the chimney (running from door along the left of the Chimney with activated command to talk to Alvin who was standing a small distance behind the chimney)
Hanged Man's Venom continues to work after it has worn off. (Tested on Gwalhir in Act IV, had no other effects on Geralt or the blade. It also works for meteorite swords and the rune sword in Act V.)
Fistfighters stall when Geralt switches from attack to dodge allowing him to quickly beat them while taking no damage.

Minor Bugs

Geralt may get stuck at the middle of a combat move, for example after clicking to initiate the 3rd combo in a sequence. In such cases, the mouse cursor will stay in the "do not click" icon (an arrow with a crossed circle), but Geralt will not swing his sword and will just stay there. Clicking again will not even give the "too fast" message. Geralt seems to just be stuck.

Workaround: Switching to another style, then back (for example, if you were in Fast style, switching to Strong style and back to Fast again) will allow him to restart the sequence from the beginning.

It is possible to have more than 1 quest dice set available from Act I and Act II
If you outdrink the Boozer in the Outskirts Inn, you cannot receive any reward for outdrinking the Boozer in the Hairy Bear Inn as they seem to be linked
When siding with the knights in Blue Eyes after having sex with the vampires, one of Patrick's squires will remain neutral (blue rather than green). Luckily, he cannot be attacked regardless.
Characters continue to be announced when entering/exiting the reception room at the New Narakort Inn when the Announcer/Herald has long gone.
Innkeeper (Male) at the Murky Waters inn charges 7 orens per night while his wife charges only 5 orens per night.
White Rayla's adjutant waiting at the transition to Murky Waters when you helped the Order during Gold Rush in Act III tells you that the purpose of helping the Order is to prevent a massacre like the one in the Outskirts. However, this makes little sense if Geralt chose to stand with the villagers in Act I rather than Abigail.
Several crypts throughout the game spawn monsters in inaccessible areas, some crypts also seem oddly linked to others, such as St. Gregory's Crypt and the Druid Cave in Act V.
Left cloister door in the Epilogue does not allow Geralt to enter.
Several doors in Old Vizima can be opened but there is no transition beyond them.
One of the lumberjacks in Act II offers to sell red meteorite but none is actually given to Geralt, under some circumstances (to be elaborated).

Quest-related Bugs

In Act IV, when trying to reconcile the Voydanoi and humans, the Lady of the Lake asks you to bring her a gift from each of the parties to demonstrate their good will. If you choose the wrong ones, go to the Lady and then go back to get another item, the old one is not given back, Geralt will keep it in his quest items for some reason. Even once the quest is complete, the right items are given to the Lady but the wrong ones Geralt picked up will stay in his inventory.
In Act IV, if talking to the Lady of the Lake about destiny before talking to Dandelion, Dandelion's part of the identity quest cannot be completed and the player loses out on experience. The "What happened in Vizima" question can then also be asked and answered endlessly without any results.
In Act IV during The Heat of the Day quest, the questlog is not updated after saving Celina the nightwraith using the wreath of immortelles. Geralt also can only tell Julian that he could not save Celina even when he did.
If following the Adam's suicide path of the Heat of the Day quest, Celina will approach Geralt at night after saving her sister Alina and talk to him. However after the cutscene talk, she turns hostile and the cutscene runs again. After she says "Woe is me" she attacks Geralt, giving him no chance to give her the wreath of immortelles. The cutscene's context does not suggest Celina should be attacking Geralt after it.
Frequently, Geralt has to leave Black Tern Island after slaying Dagon and return to have Berengar spawn for the Berengar's Secret quest to advance.
The dialogue option to talk to Dandelion about Berengar during the hostage situation in Act IV does not work properly - Geralt must talk to Dandelion about it again before going to Vizima by boat to update the quest.
When taking the vodyanoi amulet out of the altar during A Long Way from Home, there is a pop up noting "300 orens given to Yaren Bolt".
When having completed all aspects of the investigation during Act II and having spoken to the prisoner at the hospital and after then seeing Raymond at his home (and saving him), he tells Geralt that he needs to disappear for a while. The moment Geralt steps out, the Resolute Boy tells Geralt that Raymond wants to see him.

Graphical Glitches

Sometimes the textures may have random colored pixels in them, as if that part of texture memory had been corrupted. It is often a symptom of the GPU overheating, but in this game seems to happen from time to time even on a healthy video card. This, however, is not to be confused with the red blinking artifacts appearing in Geralt's vision when he has a high level of toxicity in his blood due to potions.
Sometimes a tree or other object in the distance will look like it stretches up all the way to the sky. This is generally a result of an invalid value for a vertex in a polygon, causing the polygon to stretch to the border of the screen. It is also often a symptom of the GPU overheating, but in this game seems to happen from time to time even on a healthy video card.
When drinking with Odo in Act I as part of his quest, Odo and Geralt will get stuck in the drinking motion and remain otherwise completely motionless.
When deciding to fight Vincent the werewolf and defeating him to the stage where he turns into Vincent the human: Using Aard to stun him and then using a finishing move to kill him results in Vincent still playing the stunned animation loop instead of adapting to Geralt's killing move. In the test case of "pull backwards - slash legs - fall - flash neck"
Radovid the Stern sometimes will not appear in either/both the mirror cutscenes at the Salamander base in the Trade quarter.
Creatures outside of the set AA render range play animations at approximately twice their normal speed.
Crows outside the set AA render range appear to be laying on the floor with their wings spread as if in flight.
If Geralt performs a Coup de Grace on large creatures that are knocked down by Aard, such as Wyverns, he sometimes perfoms his move where he stands rather than where the enemy lies, making it look as if Geralt was burying his blade in the ground which "somehow" kills the monster anyway.
The hair of characters passes through the body rather than flow on the body instead. see screenshot below

Audio Glitches

At the Dike in Act II, the fireplace will play a crackling fire sound even when not lit
Starting from Act III until the epilogue, a Thunder sound will play each time the player loads a save game and sometimes when the player changes into any area. (workaround available)

Other errors or inconsistencies

Neutral dwarves will say "Come of of it" when they witnessed you kill someone and walk towards them with your sword drawn. (should be "Come off of it")
In the Prologue, Geralt says "Donjon" instead of "Dungeon" in the subtitles, but only once. While donjon is an acceptable if archaic version of the same word, the fact that Geralt uses it only once and otherwise says dungeon is inconsistent.
Dwarves say "Screw Coop-Existence" which should be "Coexistence" (this could be a matter of opinion)
When Adam speaks to Alina after he has become a ghost, the subtitles read "love of my life" but Adam says "my love" instead.
Order squires give a much higher amount of experience than Order footmen or Order knights, which are weaker and tougher respectively.
Cutscenes show Geralt still using the standard model steel and/or silver swords while he's carrying swords with different appearances, like Moon Blade and D'yaebl (sword). Cutscenes in the later acts of the game will show him with two swords even if the player has him with one or no swords intentionally.
In the Prologue, Vesemir, Lambert and Eskel all have normal eyes with round pupils rather than mutated-looking eyes like Geralt's.
Putting a sephirah into an obelisk results in "Sephira and obelisk merged. The old spells still work". Sephirah is misspelled and missing an h.

Additional Information

forum thread describing official support sites
IN-GAME TECH forum thread (Not the official support site, but friendly and informative)
Fun bug shot
Geralt stuck bug
Hair glitch