Reese Witherspoon (search) is dead — but that hasn't stopped her from making another cute romantic comedy.

In "Just Like Heaven," (search) which opens this weekend to mixed reviews, co-star Mark Ruffalo (search) finds his dream apartment, only to discover it's haunted by the previous tenant.

"It's a movie about what happens when you don't nurture your spirit — could it leave you? And I think in both of the characters' cases, they are both a little lost and they go on a journey to find themselves, and have an opportunity to start again," Witherspoon told FOX News.

Playing opposite a ghost meant a lot of alone time on the set, but Ruffalo said there is one fate worse than death.

"We did the tennis ball thing with the little face on it; we did some of that for a couple days. And I like get that … take that thing down, just take it down, I don't need it anymore. Thank you. There's nothing worse than looking at a little … I can do much better with that just in my head. You know?" Ruffalo said.

Witherspoon agrees that Ruffalo had the hard part in this movie.

"I actually got off easy. I believe Mark Ruffalo got the short end of the stick on this movie because he had to do it, every time we had to do a scene he had to be there when I was there and then they would take me out of the scene and he would have to do it without me, then he would have to do it a third time where I would talk into a microphone and it would go into his earwig," Witherspoon said.

FOX News' Mike Waco and William LaJeunesse contributed to this report.