Continuity mistake: Lady Raven arrives at the Coopers' place and starts talking to the wife. Cooper's watch is set to 1:35. An instant cut later it's set to 1:20.
Continuity mistake: When Bobbie Jo holds up the jar with the spider in it and tells Hellboy that she got the cargo back, he is looking straight ahead towards the wall of the church. In the next shot angle, he's suddenly looking at her face. (01:29:16)