While the gang is running from the thugs, they dress like dancers on stage. While dancing, Slater's bra breaks, but when they are being pulled into the back of stage, his bra is together again.
After Slater makes a toast to Zack and Kelly at the film's end, he is shown walking away from them around the table. However, when the camera cuts back to Zack, Slater is again standing next to him.
When the sheriff pulls the boys over, his shirt is covered in sweat. Back at the station it is completely dry.
When Slater is retrieving golf balls in the pond on the golf course, his shirt is wet to a point, but his shorts appear completely dry. Also, in the next scene the wet spot goes higher than before but he has not been in the water anymore.
The golfer tells Slater to buy him a dozen golf balls at the pro shop, but Slater only buys 4.
When Screech distracts the golfer he's caddying for by sneezing, a large patch of grass is thrown from behind the golfer to appear as though he hit a huge divot.
When Zack and climbing across the balconies, is startled by Slater and slips he's obviously attached by a cable as both hands let go of the railing.
During the reception after the wedding, while Zack and Kelly are talking to their guests, one of the wedding guests (a female extra sitting at a table) can be seen "counting with expression". Basically, she must have had trouble faking/lip-syncing a conversation with the other extras, so instead she counts from one to about thirty, and uses facial expressions to make it look like she is having a real conversation.
Zack isn't shown to be getting a wedding ring at the altar, but he was shown to be wearing it at the end when he and Kelly leave in the limousine.
In the TV show Zack was able to freeze time by using "time out" while addressing the audience. He once did it to avoid getting punched by Slater, but he doesn't use this power to save himself and his friends from Freddie Silver and his henchmen.