Audio problem: When Ben and Jason are talking over the phone, after Jason tells Jonah, "Your mom is already there", we hear Jonah say, "Uncool man," but his lips are mouthing something different. (01:47:05)
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.