Post-1991 cars can be seen in the background where Walter and The Dude are sitting and having their coffee in the diner. Another, a black Nissan Maxima, drives past as The Dude is thrown from a taxicab in a later scene.
During the opening scene, in which the camera moves back to show several bowlers release at the foul line, one bowler rolls a translucent bowling ball. The ball, an Ebonite Clear Wolf, was not released until the mid 1990s.
When The Dude is talking to Da Fino in his car through the open driver's side window, we hear music playing on the car stereo. When Da Fino gets out of the car and the door is shut behind him, the volume of the music drops as if the window were shut.
When the Dude is told about the kidnapping, Wolfgang Amadeus Mozart's Requiem is playing in the background on Big Lebowski's HiFi. However, the timeline of the music does not correspond to the actual conversation.
In the bathtub scene, The Dude refers to the Nihilists' ferret as a "marmot" and an "amphibious rodent" yet it is neither of these things. The script originally called for a marmot, but when it was realized how big these animals are, a ferret was used instead. The dialogue was left unchanged because the Dude wouldn't know any better.
Before the Dude's car is stolen from outside the bowling alley Walter makes reference to having a million dollars "in the trunk". Later, when the car is recovered by the LAPD, the Dude looks frantically into the back seat and declares that his briefcase is missing. He never opens the trunk.
When the nihilists are ordering pancakes in the restaurant, the female nihilist orders "Heidelbeer Pfannkuchen" (blueberry pancakes) which one of the other nihilists incorrectly translates to the waitress as "lingonberry pancakes." (This may be because the nihilists don't care enough to get her order right.)
When Walter and Dude are watching Dude's landlord do his dance they are talking about the old western Branded (1965). Walter asks Dude if he remembers it and he says yeah, the Mike Connors show. It was Chuck Connors who starred in it. In addition, Walter mentions "all 156 episodes," but 'Branded' only survived two seasons and ran for only 48 episodes.
When Marty invites The Dude to view his performance, he says it will be "on Tuesday night." This night continues on, ending with The Dude asking Walter to pick him up, to which Walter replies that it is "Erev Shabbos." Erev Shabbos is observed on Friday night.
When Dude is attacked in his bathroom, there are two toilet bowl brush holders to the left of the toilet. During the course of the fight, the position of the blue holder changes - it goes from standing to lying on its side and then back to standing.
When Walter jumps out of the car at the drop-off point, he loses control of the Uzi and it shoots out the Dude's left tail light. But when the Dude recovers the car from the police, the same tail light is perfectly normal.
When The Dude is at Jackie Treehorn's and he rubs the pad of paper with a pencil revealing Treehorn's drawing of a naked man, The Dude tears the page off the pad and quickly crumples and shoves the paper into his pocket. Later while in the Chief of Police of Malibu's office and the Chief is going through The Dude's wallet, the same paper he tore off of Treehorn's pad is neatly folded in the wallet, with no sign of previous crumpling.
When the Dude is at the Malibu police office, the position of the cup of coffee of the officer changes during different shots. When the Dude falls on his desk, he puts his cup of coffee on the white paper on his desk. In the next shot the cup is on the edge of the white paper. Next shot it moves a little bit towards the officer. And then on the next shot it is again on the edge of the white paper.
At the Malibu police office the officer looks at his value club card and throws it down to the side of the white paper. In the next shot when the officer looks at the note from Treehorn's house, the value club card is lying oblique on the right of the officer's hand. In the next shot the card is lying again on top of the white paper, and partially covered by the wallet. The other objects (wallet, notes that were in the wallet, cup of coffee) also change position in different shots.
While the Dude, Walter, and Donnie talk about the carpet pissers at the Bowling Alley, the bowlers in the next lane (they can be seen behind Walter) change in incongruous ways. Watch for the big black guy and the big white guy with the pony tail. Also watch the movement of the waitress, which is incongruous. She covers 20 meters within the time it takes the Dude to say "Fuckin'-A".
In the opening scene with the various bowlers, the big African-American bowler throws an orange ball, but the ball that is shown smashing one pin against the other is blue. This is repeated with the next bowler, who throws a wine red ball but the ball that arrives is red-blue.
While driving down the road, The Dude notices that he is being followed by the blue Volkswagen. The camera shot of the Dude shows a thick layer of dirt on the rear windshield of his car. When the camera cuts to shots of the rear-view mirror to see the Volkswagen, there is no dirt at all on the rear windshield.
The first time The Dude's answering machine message is heard it says "leave a message after the beep, it takes a minute." Then there is a long pause before it beeps and Maude Lebowski leaves a message. When The Dude is smoking in his bathtub, LAPD calls and the same message is heard, but there is no delay before the beep.
The Dude tries to flick a lit roach out the car window, it lands in his lap, causing him to lose control driving and hit a dumpster. Shaken up, he looks over the top of his sunglasses out the driver's window to see if the blue VW is still following him. He doesn't see it. Immediately after, he turns his head to look out the passenger window. When he turns to look, he's not wearing the sunglasses.
In Lebowski's limo, Lebowski and Brandt confront the Dude about his failure to deliver the ransom money. When Brandt hands over the envelope with the toe, the Dude is seen reaching for it with his right hand. When the angle changes, the hand taking the envelope is a left hand. What's more, it has a wedding band on the ring finger. (After the "toilet" attack, the Dude shows his ringless ring finger as evidence that he is not married.)
When The Dude is in the bathtub smoking a joint with all of the candles lit, the Nihilists come in and throw the ferret in the tub with him. There are four candles in the corner to the left of The Dude. When The Dude starts thrashing around he puts three of the four candles out with the water and when it cuts away then goes back to him, the three candles that were out are lit and the one candle that was still lit is out.
When The Dude and Walter are making the money drop off, after Walter jumps out and The Dude crashes the car, when The Dude runs out saying "We have the money," police lights blocking off the road they are filming on are clearly visible.
When the Dude, Walter and Donny are eating the burgers they supposedly got at In-n-Out, the cups they drink from are not white with a ring of red palm trees, which is the way the cups are at that chain.
Walter draws the firearm and the Dude says, "Man, they're calling the cops." The cops show up as they are leaving. A call from Smokey and Dude and Walter's tournament advancement imply that they stayed long enough to win the round. This is presumably a sly comment on the lethargic response time of LAPD to what they consider a non-urgent call.
When the Dude is on the phone with the kidnappers, a dial tone is heard each time they hang up. However, he's not on a cellphone as some may think, rather he is on a portable car-phone. Unlike a cellphone, the car-phone would indeed have a dial tone.
After Maude Lebowski swings in and splatters paint on her piece of art, paint can be seem on the floor in front of the piece, presumably from previous splatters. However, none of the lights pointed at the piece have any paint on them, which seems highly unlikely.
In the opening credits, a big black guy throws a seven-ten split (his ball changing color from the throw to the strike, as noted in "goofs"). The first frame showing the ball striking the leftmost pin reveals that the pin isn't on the dot marking its official position. It's a little ahead of and to the left of the dot, hanging over the gutter, and the ball strikes it from the gutter: the shot is rigged.
When Walter and The Dude scatter Donny's ashes, the microphone wire under Dude's shirt is visible when Walter tries to dust him off. Also, a crew member can be seen stood atop another cliff, watching the filming.
As the Dude is making his way back from Jackie Treehorn's pad in Malibu to his own apartment in Venice, he is thrown out of the cab and passed by Bunny in her red convertible. However, if Bunny indeed had been in Palm Springs as Brandt later says, there's no way she would have passed along that route on her way home to Pasadena.