Deliberate mistake: Both in the first scene and last scene of the movie, we see Yolanda and Ringo starting the robbery by jumping from their seat and start threatening the costumers. In the first scene, Yolanda says "And I'll execute every motherfucking last one of you." But in the last scene the line changes to "and I'll execute every one of you motherfuckers". (00:04:40 - 02:18:00)
Suggested correction: Tarantino has explained that this is not an error, rather, he did this on purpose. When we first examine the scene, we are seeing Ringo and Yolanda's conversation from their perspective. Obviously, because this is their conversation, what we hear first is probably what was actually said. However, at the end of the film, what is said is different because we are no longer viewing the situation from Ringo and Yolanda's perspective, but rather everyone else in the diner, most specifically Jules.
Sounds like a typical Tarantino excuse for a stupid blunder.
Deliberate mistake: At no time can a player on the ice play without a helmet. It may be legal in professional hockey, but never in youth league games, world championships or not (This happens when the goalie comes out of the crease and takes his mask off to shoot his "knuckle-puck", as well as the penalty shot in the first movie.)
Deliberate mistake: At the elephant graveyard, little Simba claws Shenzi in the face. When Mufasa saves Simba from the hyenas, the cuts are gone, a few seconds later. [This was done intentionally, I'm sure, for two reasons. The first being, Disney doesn't let fresh scars linger on the screen too long. Secondly, during that same scene when Mufasa rescues Simba & Nala, he claws Banzai in the rear. To stress the point later in the movie, that severe scar is shown too, but only briefly, it too disappears because of reason 1. Still a "mistake", but there's why.] (00:21:50)
Deliberate mistake: In the scene where Forrest is describing his heritage, the clip of KKK on horses is taken from The Birth of a Nation. In this clip, you can see tire tracks on the dirt road well before automobiles were supposed to be in existence. Robert Zemeckis decided to leave this mistake in to perfectly match the clip to the original movie.
Deliberate mistake: When Al is looking through the binoculars, Steve's Yankee logo on his jersey is on the wrong side. (01:25:00)
Deliberate mistake: When Wade "hits" Roarke for telling his parents about the gun, it's very obvious that his hand doesn't come near the boy's face.