Continuity mistake: When the Bug's spaceship floats over Shea Stadium and the NY Mets outfielder sees it and gets conked on the head by the fly ball, he is wearing number 23. In a later scene, when J picks up the tabloid newspapers, the photo of the ballplayer has number 20. (01:20:15 - 01:29:20)
Suggested correction: Nope. The tabloid paper says the aliens made him miss a home run, referring to the batter, not the outfielder.