Don't Push - S6-E2
Continuity mistake: While trying to take a new Family Portrait, after Cameron, Mitchell, and Lily shake out their faces, say cheese and take another photo, Cameron goes to look at the laptop screen and there's a closeup of that newest photo, but when he tells Mitchell to look at the screen it's a different photo - note Lily's goofy eyes, etc.
Haley's 21st Birthday - S6-E10
Plot hole: The family mistakenly believes Hayley will be having her first drink. However, there were several instances in earlier episodes where they saw her drinking or drunk, or she admitted she'd been drinking. For example, in the episode "Arrested", the family drove down to bail her out of jail for underage drinking, and they saw the video footage, and the family members who didn't go were informed of the situation.
Character mistake: Hayley is on the phone in the car with Alex and she's holding her phone upside down.
Continuity mistake: Pepper states in this episode that he doesn't have any kids, but in 4-14 "A Slight at the Opera" he talks about a son he has who is a Navy Seal.
Continuity mistake: Whilst Clare and her new 'best friend' are talking to the flight attendant, the two glasses change from empty to full in the next shot.
Other mistake: When Claire is sitting in first class, the woman she was sitting next to finished her drink while on her angry phone call and asks for more, but about a second later she is drinking it again and it is no longer empty.
Continuity mistake: When Alex opens the door for Sanjay she is wearing red headphones around her neck, in the shot after that the headphones are gone. Two shots later, they reapear. (00:11:10)
Answer: He has seen himself dancing, and is mortified at how bad he looks.