Visible crew/equipment: When Jim walks to Nadia the first time - right after he trips on the couch - a light stand is seen right at the left edge of the screen. This was pointed out in the DVD. (00:08:57)
Visible crew/equipment: When Finch is running to the toilet, a microphone wire is visible trailing down the inside of his shirt. This is pointed out in the DVD commentary. (00:58:15)
Visible crew/equipment: In the Internet scene, Jim tosses his shirt over the webcam on top of the computer so nobody will see them. It shows one shot in Jim's bedroom of the shirt starting to slip off the computer, and the next shot is in Kevin's room seeing the shirt fall completely off. While they show the shot of the shirt falling through the computer, you can quite visibly see the hand that pulls the shirt off on the left side of the screen. (00:46:45)
Visible crew/equipment: When Jim and Kevin are upstairs at Stifler's party with the "M.I.L.F." guys, look above the top of the walls. There is no ceiling there and you can tell that they were on a built set. (00:15:35)
Answer: The song is called Sway by Bic Runga.