In a fantasy sequence, a United States of America flag is seen behind a figure of 'Uncle Sam', who is telling Bart, "It's your fault America has lost its way." The flag is almost accurate - it has 50 stars and thirteen stripes (seven red and six white) - except that the blue field containing the stars is too "tall", spanning eight of the stripes, while in the authentic flag, there are seven stripes beside the blue field, and six below it.
In the last scene, the bread on Homer's sandwich flicks to lettuce and back again several times.
Marge, just before telling Bart he can come to dinner after apologizing, places her hand on his purple doorknob. In the next shot, while the knob is still visible, her hand has jumped off screen.
Just after Homer says grace, Marge gets up to talk to the children. She walks towards the head of the table but passes in front of Homer to leave the room. The next shot shows he has his chair pushed in, meaning Marge would have had to have walked through the table.
When Marge finishes talking to Lisa about dinner and is about to leave the bedroom, she opens the door from the left side where the hinges are located.
When Patty and Selma arrive at the Simpsons for dinner, Homer calls Selma 'Patty' and Patty 'Selma'