Other mistake: Near the end when Lindsey goes to Fenway to stop Ben from selling his tickets, she borrows binoculars from someone to find him across the field. She's looking through the wrong end. The way she's holding them, everything would look tiny, and yet she still sees him.
Other mistake: When Ben gets home from the costume birthday party and laying in bed he puts the TV on when he finds out the Sox won the game. The alarm clock on the nightstand reads 10:38 when he first puts the TV on - then a couple of TV clips later it is 11:27.