In this episode Homer chooses Moe's Tavern as the location for Principal Skinner's bachelor party. This may be because since there are usually no women in Moe's, he will not be going through the same mess when he attended a bachelor party in Homer's Night Out.
When Patty brings Chief Wiggum to the house, Duffman disappears. He then reappears next to the sandwich table in the next shot.
Duffman has a Duff logo on the back of his shirt before Wiggum enters, but when he turns to make a sandwich, it's not there anymore.
In the second scene with Skinner at Moe's, he finishes his beer completely. But when the shot changes, his glass is full.
Principal Skinner's beer glass continually disappears and reappears while he is at Moe's.
Just before Homer tells Marge about Skinner's marital doubts, the car is seen parked in the driveway just fine. Moments later, when Homer asks to borrow Marge's car, the car is again seen, but this time upside-down and on fire.
During the wedding, when the band begins to play 'Just the Two of Us,' the lights are on in the gym. But when Skinner begins to dance, the lights are out and there is a spotlight on Skinner.
When Ms. Krabappel is teaching her class after the wedding sequence, she is using a chart of the circulatory system. When Marge enters however, the chart seems to magically roll itself up, and disappears.
The Hulk melon baller that Krabappel returns to Comic Book Guy disappears immediately after they are done talking about it, and the counter is once again empty.
When the school bus drives up to the school during the wedding scene, Otto is nowhere to be found. However, when the doors open and the shot changes, Otto is waiting to escort Ms. Krabappel off the steps.
Also, if Otto was waiting to help Ms. Krabappel off the bus, who was driving the bus?