Marge's necklace changes from red to white between shots.
The bullet holes in and around the TV disappear immediately.
At the beginning during the soccer game there is a close shot of Homer and Marge where Homer says to Marge "Oh I'd kill myself if Portugal doesn't win" but in this shot which partly shows Bart, he looks a different person with a long sleeve shirt and trousers stead of shorts and short sleeve.
When Homer is muttering and pacing up and down the hallway, Lisa awakens and points out that it is 3:00 am; the clock beside Lisa's bed clearly shows that it is 9:50 pm.
To make Marge feel safer about the handgun, Homer turns the safety on his revolver to the "on" position. However, revolvers do not have safety mechanisms.
When Homer is muttering to himself during the night about the 5 day waiting period to get a gun license, Lisa tells him "Dad it's 3am, can't you mutter in your room?!" but her alarm clock shows 8.50.
When the riot starts Willie says: "You Call this a soccer riot?". However, as Willie is from Scotland, he should have used the British term "football" instead of the American term "soccer".