As the 'female' is trying to break into the stable, the plank Rhys has placed to block the door has slipped down from the block, and so wouldn't prevent the doors from opening. In the next cut, it's once again wedged properly in place.
Gwen is bitten on her left arm, but when she is at the bar and checks her watch, the bandage is on her right arm and then in the next shot, it has moved to her left arm.
Jack refers to Gwen's pregnancy saying 'Haven't you heard of the immaculate conception?' This is a common error. What he should have referred to was the 'virgin birth'. The dogma of the immaculate conception refers to the belief that Mary (Jesus' mother) was conceived without the stain of original sin. Many people get these two ideas mixed up.