(at around 18 mins) When Mr. White and Mr. Pink are talking in the room about what happened, Mr. White gives Mr. Pink a cigarette and takes one for himself. He then lights Mr. Pink's but then he only holds the lighter up to the end of his own cigarette without actually lighting it.
When Mr. White and Mr. Pink are talking about Mr. Blonde going "psycho" at the heist, Mr. White says he almost took Mr. Blonde out himself. When the two later confront Mr. Blonde about his antics, Mr. White says to Mr. Pink, "You said yourself you thought about taking him out."
(at around 37 mins) When Mr. Blonde opens the trunk of his car to reveal his "surprise" to Mr. White and Mr. Pink, he puts his hand on the trunk before unlocking it. When he does, the trunk clearly moves, showing he never locked it.
(at around 59 mins) When Mr. Blonde is pouring gasoline on Marvin Nash, Nash's legs are taped to the chair. When the angle changes you can see his legs kicking up in the air. And then they go back to being taped up.
(at around 21 mins) When Mr. Pink s the woman, the satchel of diamonds is on the street in front of the door. In the next shot when he opens the door, the bag is gone. There is no time for him to have stepped forward, kneeled and grabbed the bag, stood back up and tossed it into the car.
(at around 41 mins) When Mr. Blonde is talking with Joe Cabot and Nice Guy Eddie, he brings up a cigarette towards his mouth before the shot changes. Then repeats this motion again immediately in the next shot.
(at around 1h 13 mins) During the commode story when Mr. Orange turns on the hand dryer his hand is in a gun shape horizontally. The camera cuts to on Mr. Orange's left, and his hand is now in a gun shape pointed vertically.
(at around 21 mins) When Mr. Pink is shooting at the cops from behind the car, the fat cop is seen getting shot and falling twice. Once when Mr. Pink first starts shooting and a second time when he is seen shooting at Mr. Pink.
(at around 58 mins) When Mr. Blonde walks into the warehouse after getting a tank of petroleum from his car, he doesn't close the door. But later in the same shot, when the camera rotates around the cop, the door is closed.
(at around 1h 23 mins) When Mr. White and Mr. Orange are discussing their upcoming operation sitting in a car and Mr. Orange's answering a question about "this girl's ass", we can see his right palm with smoking cigarette is inside a car. Right after a cut his hand is hanging out the window, there's no smoke whatsoever.
(at around 1h 25 mins) After leaving Mr. Brown, during the steadicam shot following in front of Mr. White and Mr. Orange, there is clearly a group of crew members in the far background on a smoke break and drinking beverages, watching the scene.
(at around 11 mins) When Mr. White brings Mr. Orange into the warehouse you see a crew member and a trailer. The door swings back at Mr. White, then opens again; the crew member realizes he is in the shot and steps behind the trailer.
Officer Marvin Nash would have died from asphyxiation and inhalation of vapor very soon after the gasoline was poured over his head. The amount of gasoline in the warehouse when ignited would probably have reached Mr. Blonde in a fireball and blown out the windows. The vapor is heavy and would have covered the complete floor in seconds.
The way to really make officer Nash to suffer for a long time would have been to pour a small amount over his legs, then ignite it.
(at around 1h 14 mins) When Mr. Orange is in his apartment and is on the phone to Nice Guy Eddie, he walks over to his window and says he'll be right down. At that moment you can see the top of the outside set piece.
(at around 1h 25 mins) Just after Mr. White shoots the cops in the scene "An Orange/White Getaway", there is a close up of Mr. Orange's face. In the reflection of his sunglasses, where there is supposed to be Mr. Brown sitting in a car, instead you see Mr. Brown sitting in a chair.
(at around 59 mins) The right-hand side of the frame is in close focus, with a blurred background. The left hand side of the frame is focused on the background. Hence there is an obvious focus discontinuity down the center of the screen.
The goof items below may give away important plot points.
When torturing Officer Nash, Mr. Blonde leaves the building to retrieve a gas can from his car. Re-entering the building, he does not close the door behind him. When Mr. Orange kills Mr. Blonde to save Officer Nash from being burned to death, Mr. Blonde falls to the floor at an angle where the door to the building is visibly closed.
After cutting Nash's ear off, Mr. Blonde walks towards the door with the opened barber's blade in his left hand. After he's opened the door he puts the left hand in his pocket and the blade has disappeared.
After Mr. Orange is shot, he is driven to the crew's hideout by Mr. White. Although Orange has received a serious stomach wound that bleeds profusely, White does nothing to stop the bleeding after laying him down. In real life, the victim would have been dead in minutes due to such heavy blood loss, yet Orange survives until the end of the movie.
Near the end, we learn that the cops are waiting for Joe to arrive at the warehouse before they make the bust. Why, then, do the police (presumably a different team) show themselves at the robbery? Because of the gunplay involving civilians.
(at around 58 mins) Stealers Wheel's "Stuck in the Middle With You" ends while Mr. Blonde is pouring a trail of gas away from the cop. The song is coming from a radio. Mr. Blonde is shot at that point in the film and never touches the radio. Yet the radio turns off for the rest of the film.
(at around 59 mins) When Mr. Orange shoots Mr. Blonde, when the camera focuses on Mr. Orange after the shooting, you can see a whole bullet roll from behind Mr. Orange instead of only the shell, which is the only part of the bullet that comes out of the gun after firing.
(at around 1h 30 mins) The squibs on Mr. White do not go off at the right time during the final stand-off. The first time Eddie shoots, the squib doesn't go off and no bullet hole appears on Mr. White. The second time he shoots, the first squib goes off. As Mr. White is falling to the ground, the second squib goes off, even though no one shot at him.
(at around 1h 30 mins) In the final confrontation between three of the crew in the warehouse, a frontal camera shot shows Nice Guy Eddie pointing a revolver at Mr. White, supposedly ready to shoot him. However, from this angle it is clear that the chambers of the revolver are empty.
(at around 1h 28 mins) When Eddie argues with Mr. Orange about the killing of Mr. Blonde, the police officer sitting dead on a chair (who was shot by Eddie a few seconds earlier) can be seen breathing.