The family in the film is American but many times Brad and Savannah slip out of their accents - due to the actors being Australian.
Around 1 hr 7 mins Brad is hit on the head by Pete and is knocked unconscious. When Jane comes in a little while later after talking with Savannah, he has a bleeding wound on his head. When Savannah finds him the bedroom, there is blood on the mattress he is leaning against, but the wound has disappeared from his head.