The Joker's design from the E3 2008 announcement trailer is dramatically different to that of his design featured in the final game.
Contributed by Boyobmas
There is a mission called "I love lamp" in which the player must decorate their base. The title of the mission is a reference to the line from the movie Anchorman: The Legend of Ron Burgundy, in which Steve Carell's character Brick Tamland says "I love lamp" when talking about love.
Contributed by Jamey Burky