When Stuart and Donnie are at the bar, Donnie shoots some pool. During one shot, he lines up on a red ball, but in the next camera angle he shoots the cue ball.
In the bar scene, Vincent D'Onofrio is standing next to Al Franken. When the shot cuts to the two guys hassling them, Vincent D'Onofrio is sitting behind them. He then reappears next to Al Franken.
When Stuart gets his show on Health Cable Network, he goes to have 20 episodes shot. The time they give him to do this is four hours, which is impossible because all the shows are 15 minutes. At least five hours would be needed, even if the cameras were never turned off.
When Stuart is reliving his recurring dream about saving his father's life, the top of the airbag is visible as the stuntman falls from the roof.