In the panning shot of Ross and Rachel in Monica's Porsche, Ross is wearing a white shirt and he is wearing a seat belt. In the interior shot, Ross is wearing a black jacket and gray shirt and he doesn't put his seat belt on until after Rachel swerves while she is putting her phone on the back seat.
When Chandler calls the others over to show what he taught Emma, Joey sits behind Chandler then in the next shot he's standing, about to sit.
When Jack and Judy are getting ready to leave, Jack is telling everyone about driving the car up on to a church lawn. Judy is standing next to Monica with both of her hands in front of her, holding her purse. The camera changes and Judy suddenly has her arm around Monica, with no time for her to have done so.
Towards the end, when everyone returns back to the apartment, Monica is sitting with Emma in her lap next to the stuffed animals. Emma is wearing a sparkly headband. When Phoebe sits down with them, after saying she just needs to be back to her massage client in 5-6 hours, it pans to Emma and she's not wearing the headband. It reappears again in the next shots.
At the beginning of the episode when Ross and Rachel tell Phoebe about the idea of video for Emma's 18th birthday, Phoebe has a plastic cup of carrots in the hand at first but in the next shot we see her gesturing and the cup is gone.
When Chandler is speaking into Ross's camcorder, blaming Emma for ruining his marriage because he and Monica couldn't get a weekend away, Matthew Perry briefly glances directly at the camera.
When Joey suggests that he, Jack and Judy give a joint present to Emma, Jack asks "which one are you?" Of the three guys, Ross is Jack's son and Chandler is his son in law, so there's no reason for Jack to confuse them.
When Ross and Rachel are driving to New Jersey to return the cake, right after Rachel yells at the student driver you can see her mouthing "s...".
When Chandler and Monica comes in to the apartment, camera holes in the wall are visible.
Judy said that her parents died very young and that heart disease kills women too. In season 1, Ross' and Monica's grandmother (Judy's mom) dies. But the grandmother was clearly not young. She was about 80-90 years old when she died. So, she didn't die young as Judy claimed in this episode.