Revealing mistake: In the scene where Charlie and his grandfather are floating from the fizzy lifting drinks, you can see the black harness Charlie is wearing.
Revealing mistake: When Charlie and Grandpa Joe drink the fizzy lifting drink and are floating in the air you can see the hook that is connected to the wire that Charlie is being held up by.
Revealing mistake: After Violet has chewed the gum and is blowing up, if you look near the bottom of her right leg, you can see the air hose that is blowing her up. Visible on full screen only.
Revealing mistake: When Violet turns into the blueberry you can see the reflection of the blue light in her hair. But in the same scenes where blue make-up is used instead of the light, you can see the regular flesh-tone under her hair and in her parting.
Continuity mistake: When Willy Wonka presses the button for the Spectacular Gum Making Machine, all of its gears and parts and contraptions start working. In one shot, a tray of a pale white chunky substance is covered by a lid. As the lid lifts off of the tray, the pale white chunks are now bright colors. You can see where the cut in the shot was made for them to replace the first tray with the second tray. There is a slight jump in the position of the lid and the misty fog in the shot changes in the same instant.
Continuity mistake: When Grandpa Joe gives Charlie the candy bar bought with the tobacco money, Joe pulls it out, holding it at the top right and bottom left corners. When the shot cuts to Charlie and he says "Grandpa, that money was for tobacco." you see Grandpa Joe in the foreground of the shot, and his right hand has moved from the top right corner to the lower half of the candy bar. When the shot cuts back, his hands are as they were before, on the top right and bottom left corners of the candy bar.
Continuity mistake: When they're in the room with Wonkavision, as Mike Teevee jumps up on the platform to get shrunk, in the background an Oompa Loompa puts goggles on, then in the very next shot he puts them on again, with no time to have taken them back off.
Revealing mistake: In the Chocolate Room, there are several see-through pipes coming out of the chocolate. The chocolate is supposed to be being sucked upwards in all of them. However, in some of the pipes it is actually flowing downwards, since it was easier for the film-makers to only pump it upwards in some of them and then send it into the other pipes to go back down. This is confirmed when Augustus Gloop gets stuck in one of the up-pipes - there is no chocolate at all flowing in one of the down-pipes while he is stuck in there.
Continuity mistake: After introducing Mr. Wilkerson, Wonka's hands magically appear on Charlie's shoulders.
Continuity mistake: On the boat ride, when Wonka explains about "The Sailor's Way", his head changes position between shots.
Continuity mistake: When Mr. Wonka is first walking toward the crowd, his walk is much longer than the actual path. Watch the shadows change on the overhead shots as the day of filming went by.
Continuity mistake: When Wonka's boat is about to depart, two shots are cut together, but the sound recorded of the second is used over both. This results in a clear view of the Oompa Loompa steering the boat with the boat's bell (and the rope to ring it) not being rung by anyone whilst you can hear it ringing - then the shot suddenly changes, and the Oompa Loompa is obviously ringing it in time to the sound.
Continuity mistake: When Wonka introduces the geese that lay the golden eggs, the geese change positions between shots.
Audio problem: In the "Candyman" song near the beginning of the movie, the candy store owner is on a ladder, about to drop candy into the kids' hands. When we see the kids holding up their hands and saying, "Me. Me.", none of their mouths are actually saying anything.
Continuity mistake: In the scene where Wonka shows the tour the Everlasting Gobstopper machine, you can see that the candy is already on the finished belt before he turns it on. In the close up of the candy, there are a lot of extra candy, but after they get passed out, the excess is gone.
Revealing mistake: Right before Augustus goes up the pipe, there is a long shot of the pipe. Look very closely. You will see that there is a dummy of Augustus, not the real Augustus.