Audio problem: When Dawson goes into his bedroom to talk to Jen, he tells her that he had an entire "impassionate" speech to tell her. It sounds like he fumbled his dialogue, and meant to say either "impassioned" or "passionate," but got the words mixed up in his head and ended up blending them together. (00:33:40)
Audio problem: When Charlie is trying to hit on Joey at the College Bar, she makes fun of him referring to him as the "Bass Player to take home to Mom" or something similar. However, when you see and hear Charlie playing in the band during that episode, it sounds like he is specifically playing either electric lead or electric rhythm or both, *not* bass.
100 Light Years From Home - S5-E19
Audio problem: When the band M to M is performing at the MTV concert, the girls start singing a song that requires a very tight harmony. During the entire time they are singing together, the camera shows close-ups of both girls. But at one point, they show the second girl with the guitar simply smiling and looking up. She is *not* singing at all, yet the song continues to have both their voices in the harmony. The rest of the bandmembers are male, and the harmony was formed by the two female lead singers. (00:13:30)
Separate Ways (Worlds Apart) - S5-E20
Audio problem: At the bar, the singer's lip movements do not match the song.
After Hours - S5-E21
Audio problem: Just after Audrey storms out of Pacey's apartment, after catching him with Alex; Pacey runs after her and they begin arguing in the street. Audrey makes a comment that 'it meant your arms around her, and HER tongue down YOUR throat' referring to The Kiss between Pacey and Alex. But then Pacey counters with 'well actually, it was HER tongue down MY throat' in sort of a comic way, as if he was correcting a backwards situation. But Audrey had just said the same thing! One of the Actors messed up their lines, probably Busy Phillips since Joshua Jackson seemed to have his lines correctly.
Answer: It's only explained once in the series. Jack says to Andie "I tried to start kindergarten without you", meaning Andie was smart enough to start school early.