* CompletelyMissingThePoint: A real-life example in that Katherine Heigl appeared to regret her role in the film (and went on to make more standard rom-coms like ''Film/TheUglyTruth'') because according to her, the film made her look stuck up because Allison didn't have fun and didn't mess around and get stoned like Ben and his crew, which ''misses the entire point of the film'' in that Ben is the one who needs to mature and get a real life to be actually ''worthy'' of being a father and being with her. The film does, admittedly, have less of an arc for Allison, but she has comparatively few faults compared to Ben, who really needs to shape up. Lampshaded ''heavily'' in a review of ''Film/TheUglyTruth'' by FilmBrain, who points out that that film treated its characters of both genders a hell of a lot worse than ''Knocked Up'' did.
* DudeNotFunny: James Franco is less than amused by Allison's vomiting mid-interview.
* FunnyAneurysmMoment: When Ben is exercising he says "I'm breathing like James Gandolfini here!" that became a lot less funny when James died of a heart attack in 2013.
* HilariousInHindsight: In the film, Jason makes a joke about Jay wanting to "rear Ben's child". When the DVD came out with some deleted scenes, Jason reveals to Ben that he more or less wants to do ''the exact same thing''! Of course he assumes the baby will be a girl, will look like her mother and he plans on waiting until she's 18.
* OneSceneWonder: Craig Robinson as the nightclub bouncer that Debbie curses out for not letting her and Allison in.
* {{Squick}}: The baby crowning scene.