When Eliot masquerades as a ballplayer, he uses a name that combines the names of the heroes of two baseball movies: the first name "Roy" from Roy Hobbs in The Natural (1984), and the last name "Chappell" from Billy Chapel in For Love of the Game (1999).
At 23:03 the tv screens behind Hardison and Parker shows the hosts of the sports talk radio show they are calling, "Sports Line with John and Danny". The pictures of the two hosts are actually those of Dean Devlin and John Rogers, Executive Producer and Creator/Writer of Leverage, respectively.
PGE Park is actually home to the Portland Beavers (Portland, Oregon).
At 40:10, although the rest of the car is shiny and clean, the front passenger door is dull and non-reflective. This is probably so we don't see the cameraman and other crew's reflection.
When Eliot makes his first out at home plate, as he tosses the ball back to the umpire, you can see that the ump is cross-eyed. Most baseball fans at some point in their life have accused an ump of not being able to see properly.