Revealing mistake: When the girls do their 'Entrapment' routine jumping through the lasers at the diamond vault, you can see them cut through the beams with their arms, legs, and hair.
Revealing mistake: When the girls are shooting at Marshal towards the end, in some shots you can see they aren't really pulling the triggers and that the muzzle-flashes have been added with special effects.
Revealing mistake: When Silent Bob is typing the message on the website about their revenge on the people who have bad-mouthed them, he just taps the last row of keys but there is a lot of writing put in the message.
Answer: Apparently it was a song that was improvised by Jason Lee and Jason Mewes. Stated on the commentary.