when hook slashes peter's arm if you put it on slow motion you can clearly see that the hook is bending slightly so that means that their was probably fake blood in side of it and when he slashes him it came out.
what do you mean 'there is PROBABLY fake blood in the hook'. what did you expect, real blood???? although i do agree that they should have made the shot properly
Dude, if you had to put it in slow motion to see it, its not a slip up.
They wouldnt have actually cut an actor for a scene, obviously.
It would be a slipup if it was noticable at normal speed, as movies are made to be watched.