Will the Real Fred Rovick Please Stand Up? - S6-E14
Plot hole: Joe says that he and Allison told people they conceived Ariel on the weekend of their wedding, even though they knew that Allison was about five weeks pregnant at that time. In episode 6.15 the plot is all about how Allison is expecting Ariel and there is a lot of talk of how she is their first child and they can't tell anyone about it because they aren't married yet. But in the season two episode "Sweet Child O' Mine" it was revealed that they were going to have a baby once before Ariel, a boy they were going to name Brian, but that Allison miscarried.
Suggested correction: What exactly is the point. She was pregnant and miscarried. So? That's not a mistake.
Pain Killer - S6-E3
Continuity mistake: When Allison is in the shower, she has total use of her right arm, hand, wrist and fingers, where in all scenes before and after she holds her right hand and fingers close to her chest and doesn't move her fingers and hand freely.