Revealing mistake: When the Babe Ruth ball is thrown to Smalls, smoke from a ball launcher is visible before Smalls hits it.
Factual error: At the last shot of the Fourth of July game of the Sandlot, high-pressure sodium area lights can be seen in the distance on the right side of the screen. This type of lamp was not developed until 1964 (two years after when this movie is set). (00:44:06)
Continuity mistake: When Wendy is performing CPR on squints the people watching it change positions throughout of the scene.
Audio problem: When Benny and the others are looking at the destroyed baseball, when Benny and Kenny are talking their mouths are out of sync with what they are saying.
Continuity mistake: When the gang are at the pool the sky changes between shots from a cloudy day to a sunny day, especially when they're kicked out of the pool.
Continuity mistake: When Squints yells "no!" and the gang run towards the fence to stop Smalls, Yeah-Yeah's hat appears and disappears between shots.
Continuity mistake: When Squints is at the pool, his hair goes from flat down to sticking up, espically when he kisses Wendy.
Continuity mistake: When the gang are jumping into the pool (minus Ham) there is a life guard watching the shallow end - in one shot he is leaning foward but when Ham says "Oh sexy" he is sitting up straight.
Audio problem: When Yeah-Yeah goes over the fence, he's panting but his breathing doesn't match his mouth or shoulder movements.
Revealing mistake: When Benny jumps off the fence, it's obvious it's a stunt person doing it instead.
Continuity mistake: When Wendy is giving mouth to mouth to Squints her head is next to his chin, but when we cut back to her she is now 5 inches away from it. Her hair also moves from the left to the right. (00:37:00)
Other mistake: When Benny signs the autograph for the fake baseball he signs it Babe Ruthe with an 'E' on the end. This can be seen when Smalls put it back in his step dad's trophy room.
Suggested correction: He did though it's apparently supposed to happen like that as one of the boys says "Baby Ruthe?" when he's signing it and a comment is made about how bad it looks. Strange as it seems; this appears to have been done purposefully for the movie thus would not be a mistake if that's what the actor was directed to do.
Continuity mistake: When Wendy sees that Squints is drowning she takes her sunglasses and whistle and throws them off the tower, but when she gets back on her tower after kicking the boys out they are back.
Factual error: The film takes place in the summer of 1962. The scene where the boys go to the local pool to swim, in actuality this is during the civil rights movement when racial injustice against African Americans was at its peak - they would have never allowed a young black child to swim in an all white pool during this year and time.
