Trivia: Ben's roommates (Jay, Johah, Jason and Martin) are all friends of director Judd Apatow and star Seth Rogan. And in fact, they are even using their real first names. Only Rogan (who portrays Ben Stone) used a fake name, and was the subject of many flub-ups, as the gang would frequently accidentally call him by his real name.
Trivia: Director Judd Apatow originally wanted to shoot footage of a real woman giving birth for the final scene in the hospital, and he even found a willing mother-to-be. However, a union dispute botched the idea, when Apatow learned that he could only shoot babies that were registered Union-members (presumably registered by their parents). This is all confirmed in the DVD commentary.