Mickey's tattoos seriously fade during the final fight scene. This is most notable when Turkish is talking to him in the corner after the third round and when Mickey imagines he has been knocked into water.
The same shot of Cousin Avi downing a pill on the plane when first flying to England is used again after he kills Tony by accident and goes back to New York. At that point, he should be wearing a purple shirt, not the yellow one with white collar and cuffs. Similarly, he gets the same taxi - 5X76 - both times.
When Bullet Tooth Tony is interrogating the fellow whose head is caught in the car window, the cut scene to his feet shows (after a bit) that he is moving at a very rapid rate. However, when the camera cuts back to the interior of the vehicle, you can tell from the motion of his torso that he is walking rather slowly.
The exterior shot prior to the scene where Turkish, Tommy, and Gorgeous George are playing cards in the caravan before the last fight is obviously taken from the beginning of the movie since it shows the door in place and Charlie outside cooking sausages. (In several scenes in between the door is clearly standing against the caravan after Turkish pulled it off.)
After Boris shoots Franky Four Fingers, he takes the ear plug out of his left ear. When he is told the stone is still in the case he turns to chop off Frankie's hand. As he does this, you can see the ear plug in his left ear.
When Boris The Blade kills Franky he says: "Fools, he could not know my name." But, actually he reacted only at the second mention of his name in that scene. Before that Vincent, in the beginning of the scene, says: "We ain't ****ing butchers, Boris".
When robbing the diamond broker in Antwerp, a fire exit sign in one of the corridors appears firstly in French and secondly, in smaller letters, in Dutch. However, Antwerp belongs to the Dutch language area and the public signs have to be first and foremost in Dutch.
Bullet Tooth Tony states that his Desert Eagle is a point 5-0 (.50 caliber). This being a Mark I Desert Eagle (noted by teardrop style safety) was never chambered for .50. Also note that he fires a total of 8 rounds in the pub, which suggests that his Desert Eagle is actually a .44 model rather than .50. The etching of "Desert Eagle .50 AE cal" on the slide is also incorrect.
When Boris is talking with his brother, his two statements are pronounced in Russian and incorrectly subtitled in English. The first statement is subtitled as "So, what should I do?", which is actually pronounced "Ya posmotryu shto mozhna zdielat" and means "I'll see what I can do". The next statement is subtitled as "It's OK. I know a couple of guys," which is actually "Da, ya ponimaiyu," meaning "Yes, I understand."
When Boris the Blade visits Vinny and Sol in the pawn shop, Vinny holds up the diamond. In the next shot, Boris the Blade asks Sol where the diamond is, and Sol says it is in the locked briefcase. Vinny had time to put it there (and can be seen doing so) and lock the briefcase, though it was admittedly not a very bright thing to do; then again, Vinny isn't very bright.
During the opening credits when Franky Four Fingers is introduced and his nickname is being explained, he's shown holding cards in his hand with a missing finger visible. It appears that when the shot follows his hand laying the cards down, all the fingers on that hand are present, but the hand belongs to Turkish, not Franky Four Fingers, and this can be viewed by slowly advancing the movie one frame at a time. The different skin tones are a dead giveaway.
When Boris first talks to Sol about the job, he offers him £50,000. When he comes to pay Sol and Vinnie for the briefcase, the amount has lowered to only £10,000. However, when Boris hears that there wasn't much cash at the bookies, he offers them the £10,000 to HELP the situation. In other words, he realizes that he promised £50,000. As a shady character, it is normal for him to cheat in this way.
When Tony intercepts Vinny and Sol outside Brick Top's place, he acts as if he knew they were going to be there. This, even though he had no idea about their deal with Brick Top. (This is, however, explained in a deleted scene.)
When Frankie Four Fingers is holding up the diamond broker in Antwerp in the opening scene, he is seen holding his Smith and Wesson 681 revolver. The trigger is nearly fully back in the trigger guard, indicating the gun is cocked, but the hammer is down, instead of also back.