Continuity: Howard shatters Dominique's slightly damaged fireplace slab with a chisel and says, "Now it's broken and has to be replaced." When Dominique asks Howard if he can replace it, the next shot of Howard shows him kneeling in front of the not-yet shattered marble slab.
Revealing mistakes: When Cameron smashes the window in Roark's office, you can see that the flag outside the window flying in the skyline is not rippling and therefore is part of a photographic backdrop rather than a live location.
Continuity: When Roark is having his first meeting with Toohey he has a copy of the Banner in his hand. When Roark says "I read that in your column yesterday" the paper in his hands is open. The scene shifts perspective to Roark from behind and the paper is folded.