The Notebook star plays an aspiring news producer in the upcoming romantic comedy, and one sequence sees the actress getting steamy with Wilson.
But the scene left McAdams with a string of injuries.
She tells the Sydney Daily Telegraph, "I got bumps and bruises doing the love scenes because they wanted us to be kind of tumbling as we got in the bedroom.
"Roger (Michell), our director, thought it would work if we were rolling around. Awkward at first, like always, but this one had to be so mapped out because of the kind of comic moves that Patrick and I do that there was more laughing than any kind of embarrassment."