Wasn't Jolly a vegetarian?
In the scene where they are at the dinner table discussing Jolly, her mother mentions that Jolly had a maxim that he 'didn't eat anything with a face.' However, as a ghost, Jolly orders a cheeseburger with some very specific instructions (medium rare, hold the onions)... I know he doesn't actually eat the burger, but it seems a little odd that a vegetarian would have such specific preferences for a meal he didn't eat in real life... especially refusing vegetables on it!
My only explanation is that Jolly wasn't REALLY a vegetarian, it was just something he 'put on' for his life with his wife; this could be an indication, early on, that he wasn't really the man she thought he was (with the cheating, etc.) However, his wife doesn't seem at all surprised at his order, so if this were the 'movie' explanation, I feel like she would have brought it up.