Revealing mistake: In the middle of the movie, Roy is flossing his teeth by himself. In the mirror as well as when he turns around, you can see his hand holding the hook, if you look closely. (00:58:33)
Factual error: During the movie, which is based in '79, Roy has a Rhino bowling ball. Rhinos weren't made until '85.
Revealing mistake: Just when Ernie Mcracken wins the $1,000,000 and everybody crowds round to talk to him, you can clearly see Roy's hand popping out (and I think that the hook is hidden in the towel he has). (01:34:50)
Continuity mistake: The handles move on the foosball table during the scene at Stanley's house, even though nobody was near the game.
Continuity mistake: When Bill Murrary is bowling his last frame in the finals there is a man 4 rows up standing right next to the ESPN booth on the left side of the screen. In one shot he has a brown jacket on but in another the jacket is gone and then back on again. (01:40:50)
Factual error: In the scene that takes place in 1969, the car in the garage next door is a 1973 Buick.
Continuity mistake: When Munson is on the bridge right before he backs up to tell Ishmale he passed the test, he has a vision in his mirror of his nasty landlord. When the vision ends he folds his mirror up, but the next shot when he's backing up, the mirror is back to it's original position.
Factual error: The US postal logo shown on the postbox was not used until after 1979.
Other mistake: At the start of the tournament, Big Earn steps beyond the foul line in his first frame.
Continuity mistake: In the final match between Roy and Big Ern, Big Ern throws his second ball in the tenth frame and has removed his silver neck scarf thing, but when he turns towards the crowd, the camera angle that shows the back of Big Ern shows the scarf around his neck once again.
Factual error: During the video montage after Roy, Claudia and Ishmael decide to go to Reno, Ish is seen sitting up in the back of the convertible. There should be a lot of wind but Ishmael's hair doesn't really move and he is even able to light his "smoking device" despite being in the open air. Toward the beginning of the scene Claudia and Ish are dancing in the back of the car and Claudia's hair is being blown around.