Trivia: This is for the trailer rather than for the final film, but worth a look. At 1:33 in the trailer, just after seeing Rorschach slam someone against a wall, we see another fight. Pause it and look at the guy in black - he's holding a walkie-talkie, which in the next shot becomes a gun. This is only trivia, not a mistake, because it's only valid for the trailer. The MPAA don't allow guns to be pointed at the screen in trailers, so Zack Snyder, in a tribute to the infamous gun-editing from E.T., replaced the gun in that one shot with a walkie-talkie. (00:01:30)
Trivia: During the Battle of Vulcan, as Sulu goes under a piece of another starship, you can see R2-D2 go flying past just over his shoulder. (00:47:35)
Trivia: Ron Howard's father, Rance, makes a cameo as one of the Cardinals locked in conclave. (00:32:10)