Continuity mistake: When he hits the ball off the clock, everyone leaves the park after his home run. Why should they? Roy Hobbs' team is the visiting team, so the Chicago Cubs still have their turn at bat in the bottom of the ninth.
Continuity mistake: In many of the newspaper clippings of Hobbs' feats, the words under the headlines talk about tennis or the society page - not baseball.
Continuity mistake: At the end of the movie, Hobbs hits a foul ball and breaks his wonderboy bat, however, when he hits the final home run and the camera shows him looking up towards the lights and his bat is in full follow through, you can easily see that it is the wonderboy bat, as the lightning bolt is visible.
Continuity mistake: When Roy breaks his bat in the playoff game, the bat is a long way from the batter's box; the "Wonderboy" fragment is lying further away from the foul line than the rest of the bat, and the fragment "point" faces away from the foul line, the top of the bat on both parts face the line. However, in the close-up, the fragment is facing the other way, with the point facing the foul line. Note, too, that when Hobbs hits the ball, the bat is not split. (02:09:10)
Continuity mistake: When Hobbs goes to bat for the first time, just before Hobbs hits the cover off the ball, it cuts to the pitcher with the ball in his hand, behind his back. The ball he is holding is a clean, white ball, tightly stitched. When Roy hits the ball, it changes to a dirty ball, you can see this when they go to field the ball and all he has is the cover, it's much dirtier than one hit would have made it, even in the rain.
Continuity mistake: At the beginning of the film, the young Roy breaks a board of the hen-house wall with a pitch. When the shot cuts back to the hen-house wall a moment later, the hole is a different shape and in a different place.
Continuity mistake: During the scene in the coffee shop after Glenn Close has come to see Robert Redford play baseball, his lemonade is full with the straw standing straight up. In the next shot, his lemonade is less full with the straw leaning to the side, but in the shot after that, the lemonade is back to full and the straw is straight again.
Continuity mistake: When Roy Hobbs knocks the cover off the ball, he is shown sliding into third base, jump up and covered in dirt and mud on the right side of his uniform pants. They then show him standing on third base in a downpour while everyone argues about the ball. In the next scene, he is shown walking down the hall with Pops and a bunch of reporters talking about what he just did, completely dry in a clean uniform.
Continuity mistake: When Red an Pops are shaving and Pops is talking about wanting to be a farmer then Roy is talking about what it's like living on a farm. Notice Pops' shaving cream. It starts out with a opening on his left cheek beside his chin. Then all of the sudden it changes to show all of his chin and his cheeks are covered with shaving cream.
Continuity mistake: How does Roy Hobbs finish the last game with only 3 at bats? He's batting 3rd, it's the top of the 9th, and the announcer says Hobbs is 0 for 2 so far (says nothing about a Hobbs walk). It's impossible for a 3rd place hitter to only have 3 at bats if he's hitting in the 9th inning.