Audio problem: When Charlie and Grandpa Joe are first being lifted into the air after drinking the fizzy-lifting drinks; Charlie tells his Grandpa that it's ok. But instead of saying "Grandpa", he very clearly says "Grandma".
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.
Revealing mistake: At the beginning, in the candy factory, Bill (the store owner) is handing out candy left and right and singing to the kids. There is a shot where he turns around and a girl is pretending to throw candy into her mouth. Clearly her hand is empty.
Continuity mistake: On the boat ride, when Wonka explains about "The Sailor's Way", his head changes position between shots.
Continuity mistake: After introducing Mr. Wilkerson, Wonka's hands magically appear on Charlie's shoulders.
Continuity mistake: When Veruca tells her dad that she wants a golden goose the stuff in the bowls behind them keeps changing.
Visible crew/equipment: In the scene where the group enters the weird elevator with the escher wallpapered walls when the shot looks from the back of the elevator you can see the shadow of the camera/light reflector on Mr. Salt.
Continuity mistake: When Wonka is leading the group down the stairs into his factory, Veruca's right arm changes position from her hand on the bannister to her entire forearm resting on it.
Continuity mistake: A tree suddenly appears behind Grandpa Joe, Charlie, and the Beauregard's that wasn't there before, as they rise to see Wonka emerge from his factory.
Continuity mistake: After Wonka tells Mr. Salt a waterfall mixing chocolate gets it just right, both men are very close together, but the next shot of them shows Salt further away from Wonka than before.
Continuity mistake: In the scene after Charlie brings home the loaf of bread, his mom moves in front of the television set near Grandparents George and Georgina, but the closeup of George and Georgina shows Charlie's mom nowhere near the TV set.
Continuity mistake: When Wonka enters the shrinking corridor, he pauses in front of the wooden door, to the right of the viewer but the next shot shows him further to the left.
Continuity mistake: When Charlie gives his pay to his mom, Grandparents George and Georgina are asleep but their head still change from lying at an angle to straight as the shots change.
Continuity mistake: Outside the Inventing Room, Veruca and her father stand about a foot apart from each other, but the next quick shot shows Veruca standing in front of her dad's left arm.
Continuity mistake: When Augustus falls into the chocolate river, Wonka's right hand is resting on the top of his cane, which is planted in the ground, but the next shot shows his right arm up, and bent at the elbow.
Continuity mistake: When Veruca throws the golden wrap at Wonka, the table holding the wrapper is head-on to the viewer, implying Wonka's point of view, but after Veruca throws the wrapper on Wonka, the table is off screen and 90° to the left of Wonka and the other factory guests.
Continuity mistake: In the "I Want it Now" musical number, Veruca grabs some golden egg wrapper and throws it on Wonka. When she does, the table with the wrapping is immediately behind her, but when the scene cuts to her after she has thrown the wrapper on Wonka, the table has disappeared.
Continuity mistake: When the guests enters Wonka's Fizzy Lifting room, Veruca Salt and Mike Teevee are standing next to each other, when Mike turns away from Veruca and takes a step. The next shot shows them both close together again.
Audio problem: When Charlie and Grandpa Joe are singing the "Golden Ticket" song, Grandpa Joe says, "Watch my speed!", but his mouth does not move to match the words.
Visible crew/equipment: When Wonka finishes handing out the Everlasting Gobstoppers, you can see the shadow of the cameraman on Wonka as he walks away.
Chosen answer: In the original book, Charlie has an obsession with chocolate that he only satiates once a year on his birthday. Also, at this point in the book, the Bucket family is going through an extremely hard time and Charlie has had less food than he usually would have, so he is EXTREMELY hungry.