Continuity mistake: When Ren is dancing at the drive in, he starts dancing with a girl then stops to watch her. When he starts dancing again he moves slightly in front of her in the shot. Then in the next shot they are side by side.
Continuity mistake: When Ren and Ariel join Willard and Rusty in fighting Chuck and his friends, Chuck says to Ren "Why don't you come down here." As he says this he makes a "Come over here" gesture with his hand. The shot is from behind him, but then when it switches in front of him his hand is already down by his side before he put it down in the previous shot.
Audio problem: When Ren has his cousins teach Willard how to dance, he and Woody watch and comment. At one point Woody says "Less hips" and Ren says "A little less". When Ren says this his mouth isn't moving.