Just three episodes earlier, the newscaster on television said Barney's Bowling alley had burned down.
The filling of Homer's sandwich changes from green to purple.
When Marge is on the phone with her sisters, her necklace is white. Then they cut to Patty and Selma, and then back to Marge. Marge's necklace is now its normal color.
The house windows change from bay to arch at some points.
When Homer is at lunch with Lenny, his sandwich first looks to have lettuce inside. In the next few frames, it looks like peanut butter and jelly. Then, it looks like a meaty sandwich.
If Marge is 34, this would mean she gave birth to Bart, now 10, when she was 24. This is inconsistent with most flashbacks to Homer and Marge's earlier lives.
When Marge is seen twice putting on bowling shoes, she is putting them on her bare feet. In real life, you need to wear socks with bowling shoes in order to prevent the spread of foot fungus.