Pun Salad

Nathan Filion, ex-Captain Mal from Firefly, is the primary hero, a small-town cop finding himself well over his head when he's called upon to save the world from invasion by zombie-creating space slugs. He's perfect in this role. He's aided by Elizabeth Banks (playing the wife of the initial infectee) and Tania Saulnier (the only member of a farm family to escape zombifcation); both prove to be more resourceful than might be expected.

Jenna Fischer, Pam from The Office, has a small role; it involves adopting a twangier accent and bigger hair. Trivia: in real life, Ms. Fischer is married to James Gunn, the writer/director of the movie. And she seems so normal.

Also, you'll want to hang on through the credits for the final scene. (Which is kind of a cliché for films of the genre, but never mind.)