Future Tense - S4-E4
Continuity mistake: When Pacey picks Joey up to carrying her out of the party, he puts her over his right shoulder. In the next shot, just before they go out the door, she is carried over his left shoulder.
Future Tense - S4-E4
Continuity mistake: During this episode, Jack injures his left shoulder playing football and has to wear a sling the entire time. Every single time Jack is shown, he is wearing a blue sling on his left arm, with the supporting strap across his right shoulder (to provide diagonal support), except once. During the party scene when Jack is talking to Dawson - the blue sling is suddenly over his right arm, with the supporting strap across his left shoulder. This scene was actually shot with the sling on the correct arm, but was "flipped" to make it fit with the direction of the next scene to follow. (00:29:45 - 00:33:40)
Future Tense - S4-E4
Continuity mistake: When Joey is being helped down from her seat on the dock, her cup changes instantly from being in her left hand to her right.
Future Tense - S4-E4
Continuity mistake: When Pacey walks around the poker table to where Joey is sitting, Joey's hands go from in front of her holding cards, to flat down on the table.
Future Tense - S4-E4
Continuity mistake: When Jen is helping drunk Joey down from her seat on the dock, in some shots Jen is holding her hand to help her down, and in other shots she has her hand around Joey's waist.
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.