Other mistake: In the scene where we see Professor Bruttenholm talking to Myers about Abe's origins, we see the professor pick up what he specifically describes as "rotten eggs" from an open bowl and place them into a tube. The eggs have been sitting out in the open the whole time, but Myers only reacts to the smell once Broom picks them up.
Other mistake: All the time that Abe has been underwater reading multiple books at a time, he's never designed a machine to turn the pages? Even a pointer on a long arm would work serviceably. (00:19:50)
Other mistake: Every time someone gets skewered through with a blade in this film there's never any blood on the blade afterwards. (00:41:50)
Other mistake: During Hellboy's second encounter with Sammael, at one point they crash through the ceiling of a subway station, causing panic. Watch closely when they first fall through and you see shots of the crowd reacting and running away... In at least two different shots, you can see an Asian female extra with dark hair who is not only looks completely disinterested, but is moving at a slow, leisurely pace while everyone else is running.
Other mistake: When the camera pulls up from Hellboy embracing the dead Professor Broom, you can see that several of the evidence numbers are present more than once. Evidence numbers exist to identify and correlate different pieces of evidence without doubt in photographs of the crime scene. It would just be nonsensical to re-use them on different pieces of evidence on one and the same crime scene.
Other mistake: At the train tracks, before Abe enters the water, he turns his blue locator off, but, later, one of the agents blue lights goes on and he says "Hey, it's Abe." But Abe doesn't turn his locator on until he leaves the water, injured and in need of help.
Answer: The internal machinery that powers him is clockwork. It needs to be wound like a watch every so often. He releases most of the tension when he fakes his death.
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