Continuity mistake: When the Dude is in Jackie Treehorn's estate, he pencils over a pad of paper to see what Jackie wrote down while he was on the phone. He then hurriedly crumples up the piece of paper and shoves it in his wallet. Then, when we see the Chief of Police of Malibu looking through the contents of The Dude's wallet, the paper is there, neatly folded in fourths.
Continuity mistake: The Dude is driving, being followed by Da Fino. Suddenly he realises the tail has disappeared and hurriedly pulls the car over. As he looks out his driver's side window, we can see he's wearing his sunglasses, but when he checks the other window, his sunnies are gone.
Continuity mistake: When The Dude enters Lebowski's office the telephone is on the far right of the desk and the lamp is on the far left with 3 wooden objects between them. During the shots of The Dude, when he is talking, the phone and lamp are much closer together and the wooden objects aren't there.
Visible crew/equipment: When the Nihilists are ordering food at the restaurant, you can see the reflection of the camera and cameraman in the window behind them. Watch as the scene pans around and you can see the camera and the cameraman move as well. Could the person behind the camera be Roger Deakins?
Continuity mistake: There's one scene where The Dude is taking a bath, and three Germans threaten him with a marmot (actually a ferret). When they take the little animal out of the water, you see Dude's head and in the back four candles: yellow, blue, red and white. The yellow and red one aren't burning; the blue and white are. The next shot of the Dude's head you see that the yellow, blue and red candles are burning, the white one isn't.
Deliberate mistake: When we are introduced to Jesus, during his slow motion roll, the camera cuts to the ball hitting the pins and then back to Jesus doing a celebratory dance. For some un-known reason, the film of the ball hitting a strike is actually back to front (see the posters above the lane are in mirror image to what they should be). Given that a bowling lane is perfectly symmetrical, if anyone's got an explanation, I'd love to hear it... [Jesus bowls with his right hand. If the scene was played the correct way, you would realize the shot of the ball rolling was done by a LEFT HANDED bowler...so obviously rather than re-shoot the scene with a right-handed bowler they reversed the shot. Voila. Still a mistake but there's why.]
Continuity mistake: When the Dude shows up at Maude's place (the time where the video artist is laughing annoyingly), pay attention to Maude's bangs changing positions between several shots. Sometimes the hair is raised up on the left side of her forehead and other times the bangs are straight across. It's most noticeable after she pours a drink and turns around.
Continuity mistake: When the Dude joins Mr. Lebowski in the West Wing, where he was in seclusion, he is handed Bunny's ransom note by Brandt. As he reads the note he smokes a joint. Through the entire reading sequence he moves the joint from his mouth to his hand and back. Watch how several times the joint is in his hand, while you see a shot of the note and the Dude's hands, but when the shot changes to overall view, the joint is suddenly back in his mouth and he retrieves it again.
Factual error: This film takes place in the early 90's. When Walter and the Dude are talking about the toe in the cafe, you can see late model cars driving by on the street, such as a late model Ford Explorer and a Cadilac. This is also evident when the Dude gets kicked out of the cab and a mid '90s Nissan Maxima drives by.