Continuity mistake: When the treehouse is about to explode, we see Bertram say he's getting out of there and go down the ladder. Then after some scenes we see him running out of the tree house when he was supposedly already down on the ground.
Continuity mistake: When Smalls tries to throw the ball for the first time, everyone laughs at him and falls down. When it shows the guys from Smalls' view, it shows Yeah-Yeah falling down. Then when Smalls is running away, it shows Yeah-Yeah falling again.
Continuity mistake: When the fence is about to fall on the dog, it changes camera angles. In each camera angle the fence falls in different directions. Plus when it starts falling, the dog turns around facing the fence, but when it falls on him, he is facing the other way.
Continuity mistake: Scotty Smalls has a black eye the second day he goes to the sandlot. After Benny teaches him how to catch, he turns around and looks at the fence, and his black eye is healed. When when we see him going home his black eye reappears.
Continuity mistake: At the end when Benny gets the ball and runs from the beast he hops the fence. The ball is in his right hand as he jumps. When the gang helps him up, he doesn't have the baseball in his right hand. As he's running through town the ball is back in his right hand.
Continuity mistake: A while into the chase scene at the end of the movie, the dog chases Benny through the founders' celebration. A large cake, about four or five tiers high, is being carried by a couple of bakers. They lose their balance and set the cake down, but eventually it gets sent into the air. While going up, it stays whole, but the shot changes when it's coming down, and it has now broken apart into many small pieces.
Continuity mistake: It is established that "The Sandlot" is a relatively vacant lot, mostly dirt, with grass mostly in the infield areas. But numerous times in the scenes involving trying to retrieve the baseball, the background shows a manicured yard with a yellow house just off to the side. It's not in the distance, it's right next to the treehouse. And it doesn't appear that this is just another angle, as we see the treehouse from a distance numerous times, and there is no grass or house anywhere in its area, let alone a full back yard with a grill.
Continuity mistake: After Squints kisses Wendy and the boys leave the pool area, Ham asks Squints if he planned it, and he looks back at Wendy. When the shot changes, some of the boys change position. For instance, Timmy is standing before the shot change, but sitting immediately afterward. (00:40:55)
Continuity mistake: When Wendy is performing CPR on squints the people watching it change positions throughout of the scene.
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.
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.
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)
Continuity mistake: During one attempt to retrieve the ball, the boys use a pot attached to a long piece of angle iron. When they flip the whole contraption over to grab the ball, the part of angle iron outside the fence is still facing in the original direction.