You know that the werewolves versus vampires film Underworld has spawned three sequels, with a fourth, Underworld: Blood Wars, coming soon. But did you know that when director Len Wiseman was developing the first Underworld, he got too ambitious with his story? Eventually he realized that his screenplay was getting to dense for one film. Rather than condensing everything to fit into a single movie, he removed whole sections so that they could be used for future sequels. That’s just one of the blood-sucking facts featured in this new episode of You Think You Know Movies!

In the last film, Underworld: Awakening, Kate Beckinsale’s Selene discovers she has a teenage daughter. On the same day Beckinsale was supposed to see an audition tape from a promising actress for the role, she went shopping at Barnes & Noble with her real daughter, where they saw a young woman who bore a striking resemblance to her. Incredibly, that woman, India Eisley, was the same actress on the tape, and she was later hired to play the part. So let that be a lesson to you all: Keep going to brick and mortar bookstores! You never know who you’re going to see there.

‘You Think You Know Movies?’ is a ScreenCrush original series that dives deep into the cinematic worlds of your favorite movies and freeze frames a few tidbits you might not have known. We’ve already tackled Star Wars, The Avengers and Spider-Man, but now it’s time to hunt some werewolves (excuse me, lycans) and learn about the Underworld series. Watch more installments of ‘You Think You Know Movies?’ below and let us know in the comments what movies we should cover next.