Continuity mistake: In the scene where Tom Hanks goes back to his mother's house when he's "BIG", he tries to convince his mother it's him by telling her his birthday: November 3rd. However, in the scene (with John Heard and Elizabeth Perkins) showing the milk carton of Tom Hanks "missing" as a young boy, his d.o.b. is shown as 1/20/75. (00:16:50 - 00:53:05)
Continuity mistake: When Josh just becomes big, he hands his baby sister a wallet. She lowers her hands beneath the border of the playpen. The immediate angle, barely a frame later, shows her hands above it. (00:14:45)
Continuity mistake: The morning Josh becomes big, one of his sneakers in the bedroom swaps from being underneath the bed by the coat sleeve, to half a meter away in a different position.
Audio problem: In the scene when Josh (as Tom Hanks) comes back to his house to talk with his Mother for the first time since becoming "big", she starts screaming and backs away from him. She backs into the piano she says "Go away, go away." but her lips don't move at all. (00:16:45)
Continuity mistake: When Tom Hanks is playing the piano in the toy store you see a man in the crowd lift his daughter onto his shoulders 3 times. (00:49:20)
Continuity mistake: When Josh and Billy are in the equipment room note the orange and blue pads on the middle shelf. The blue pads change, their white strap goes being tucked up to hanging down then they disappear completely and reappear between shots. (00:16:35)
Continuity mistake: When Josh and Mr. MacMillan first meet in the toy store Josh's collar is up. Mr. MacMillan says, "Come On." They walk around a corner and Josh's collar is now turned down. (00:37:35)
Continuity mistake: When the camera first pans up to Josh on the top bunk as "big," note his coat on the bottom bunk: The letters on the back are pushed together and three are barely visible. Yet when he returns from the bathroom moments later the coat is noticeably more spread out and many more letters are visible. (00:11:00 - 00:12:50)
Continuity mistake: When Tom Hanks and his boss are playing the oversized piano, a young girl in the background is seen to sit on her dad's lap twice. Also, the boy in the sweater disappears, then reappears in time to applaud at the end of the song.
Continuity mistake: When Josh and Billy arrive at the hotel, the concierge takes his hand with a cigarette to his mouth, but from opposite angle his hand is down counting the money.
Continuity mistake: During the opening credits, when the girl shows up, Billy's hair is messed up on the wide shots, but combed in the close-ups. (00:02:50)
Continuity mistake: In the Pizza Place when they bring out Josh's birthday cake note the amount of soft drink in Billy's glass. The amount drops significantly from when they approach with the cake to the close up of the cake on the table where the glass is nearly empty. (01:06:45)
Continuity mistake: When Josh hands his wallet to his baby sister, she turns and walks to the center of her playpen. In the very next shot, she's leaning up against the railing again. (00:14:45)
Continuity mistake: After payday, Billy and Josh are in the hotel and foam suddenly appears on Billy's previously spotless face, only to to clean itself up half a second later. (00:43:35)
Revealing mistake: At the end of the movie when Josh and his friend are walking down the street, a lady crosses the street in front of them. Look closely to the left of the screen. The lady is obviously behind the tree waiting for her cue because she is not seen walking toward the tree before crossing the street. (02:06:40)
Continuity mistake: After Josh makes his wish, a shot depicts the older kids run behind the tents. During this shot, the camera shows a side view of the Zoltar machine. You can see the head stop moving up and down, and the breathing sound continues. After Josh reads the card, the head is moving again. (00:09:15)
Continuity mistake: When the shot first enters the bedroom the morning Josh becomes big note the yellow truck at the foot of his bed, it is away from the lower left corner and facing out. When Josh jumps down from the top bunk it is flush with the bunk and facing the other (right) foot of the bed and remains in this position for all remaining shots of the bedroom. (00:10:50)
Continuity mistake: Susan's hands change position on Josh's neck as she says goodbye at the end. (02:04:10)
Continuity mistake: In the toy store, Josh throws himself playfully to the floor as if he had been shot. The square receiver on his chest swaps from being on his right side to being the center of his chest between shots. (00:46:50)
Continuity mistake: John Heard's racquet jumps from one hand to the other when he and Tom Hanks fight on the tennis court. (01:17:20)
Answer: According to imdb: Though some believe it to be Colossal (Cave) Adventure or an early Sierra Game, no known game up to 1988 accepts the commands "melt ice wizard" or "throw thermal pod" (as used in the movie), therefore one can assume the game screen was simply created for the movie.
Carl Missouri