Continuity: When Lando says "Go on, you pirate" his entire outfit is reversed - his shoulder holster strap goes the other way, and his rank insignia changes side too.

Revealing: During the scene when Dorothy and Scarecrow are fighting with the trees, Scarecrow says "I'll show you how to get apples" and he gets hit by the apples. The very next scene if you quickly look at Dorothy's shoes, you can see that she is wearing black shoes, not her ruby slippers.

Visible crew/equipment: In the "Battle of Carthage" in the Colosseum, one of the chariots is turned over. Once the dust settles you can see a gas cylinder in the back of the chariot.

Revealing: In the shot where we see all the terrorists (except Karl and Theo, who are upstairs) walking into the building from downstairs, they are about to walk through a doorway when the camera cuts out. Watch the terrorist on the left (he's the one who guards the door) - before the camera cuts out he realises he's about to hit the doorframe very hard. Reminiscent of the Stormtrooper in Star Wars.

Revealing: When the swordmaker writes "Bill" on the window, take a close look. The window has been wiped before (as happens at the end of the scene) and "re-steamed" - you can see the outlines of the wiping from earlier takes, with a clear contrast between that pane and the others.