Continuity mistake: When Richie and his brother Bob get into a fight, Bob pulls on Richie's sweater and yanks his tie out of kilter. A few seconds later, Richie's tie is tucked in and his sweater is smoothed down, but not enough time has elapsed for him to have done this to himself. (01:00:34)
Continuity mistake: In the scene when Bob takes Ritchie to "get laid", Bob approaches the girl in the pink dress at the end of the row, while Ritchie goes to play La Bamba. You see Ritchie play La Bamba and in the background Bob is all over that girl. The next shot cuts to Bob just arriving at the girl.
Continuity mistake: When Ritchie is driving, it shows the speedometer at 80 mph, but in the wider shot he's obviously going much slower. You can tell by how fast the lines on the street are going past.
Continuity mistake: When Donna and Ritchie are riding in Donna's convertible they're going relatively fast, but Donna's hair is hardly blowing at all.
Continuity mistake: When Ritchie's brother lies down next to him in his bed, the covers are down to Ritchie's stomach whenever they show him in a solo shot, but are pulled up almost to his neck when the shot shows both brothers together. In the next solo shot of Ritchie, the covers are back near his stomach again.
Continuity mistake: When Richie is showing the new house to his mom, Bob on his car says OK, lifting his hand, but in the next shot his hand is down.
Continuity mistake: At the bar in TJ Ritchie gets to the stage to hear the song, but in the next shot he is a few feet away.
Continuity mistake: While Ritchie speaks with Rudy about his audition, Rudy has an empty bottle of coke but in the next shot the bottle is full back again.
Continuity mistake: After Ritchie has a gig at the cowboy bar, he is taking breakfast at home and the amount of food on his plate increases and spreads out.