Plot hole: When Joey walks into her class and sits down, her cell phone rings and her Professor answers it. As he listens to Audrey on the other end, he says very quickly that he got the message. But when he relays the entire message to Joey after he hangs up, the message is much longer. There is no way he could have possibly gotten that long a message in the very short time he was talking to Audrey and said 'he got it'.
Continuity mistake: At the very end, Dawson and Joey are kissing and they lay back on her bed. The snowglobe Dawson has just given her sits on the table next to her bed, and suddenly the snow inside it is drifting vertically down as if someone has just shaken it. But Joey and Dawson are busy, and neither one has touched it. Only a strong shaking could produce that type of snowfall, not just something bumping the table.
Continuity mistake: At the beginning of the episode, Joey is shown refunding her Paris ticket. The shot is from Season 5 Finale, and her hair is tucked back behind both ears and darker. The next shot of her, the hair is suddenly much lighter, wavier and hanging in front of her ears. Obviously this was shot in Season 6.
Factual error: When Joey is talking to the Professor, he mentions that her Birthday is the next day. Dawson also helps Joey celebrate her Birthday early at Midnight that night. Clearly this is some time in early Fall, when the Semester first starts at Worthington; probably August or September. But during the Season 5 Finale, Bessie hands Joey her Passport which has Joey's Birthday listed as May 13, 1983. Also, in previous years of the show, Joey's Birthday was never shown to be in the Fall. She didn't even start learning to drive until later in Season 3.
Continuity mistake: During the beginning intro monologue, Jen is shown seated between her parents on a couch. The two actors portraying her parents are only shown from the back, but they appear to be different people than the original actors who portrayed them. The father, especially has different hair and wears glasses.