To accentuate the contrast between the scary and the funny, director Paul Feig made the decision to shoot the movie like a brightly-lit comedy. "Thrilling things happen in the daylight rather than in darkly lit rooms." He adds, "in the suburbs, there's not a lot of hiding among the white walls and bright windows."
Anna Kendrick thinks that many women will be able to relate to Stephanie (Kendrick) and Emily's (Blake Lively) friendship because "Stephanie also wants validation from Emily." Kendrick says, "She's willing to put up with a lot of abuse because it's preferable to her loneliness."
The scene where Emily (Blake Lively) swats Stephanie (Anna Kendrick) on her backside with the back of her hand was improvised by Lively; she believed it was appropriate for her character. Kendrick's yelp of pain and surprise was genuine.
When Emily makes her first appearance and is walking from her car in the rain, an umbrella blows past in front of her. This is a reference to a trope in almost every spaghetti western ever made, when two gunslingers approach each other and a tumbleweed blows by.
Emily Nelson is a heavy drinker. In stark contrast, Blake Lively does not drink alcohol. In an interview she stated, "I don't drink. I've never tried a drug. It's just something that I genuinely don't have a desire for."