It is stated that people change into werewolves during the full moon, yet they mention that the characters will turn into werewolves for the next four nights. A full moon does not last four nights in a row, it happens only once every 29 or 30 days.
The goof item below may give away important plot points.
When Henry Hull is attacked by the Tibetan werewolf, the insert shot clearly shows him being bitten on the arm. Later in the film, however, when the arm wound is shown, it does not resemble a bite (or puncture) wound at all, but rather two very long slashes running the length of his arm.