In the DVD commentary, it is mentioned that Paul Feig and Kristen Wiig made a deliberate decision for Annie to keep her bra on during her sex scenes with Ted (Jon Hamm) but to have her take it off during her sex scene with Nathan (Chris O'Dowd) as a way of symbolizing that Annie feels she can open up emotionally (as well as physically) to Nathan in a way that she can't to Ted.
Jon Hamm chose to go uncredited as he felt his presence on the credits would signify a more serious film seeing as he, as an actor, is not generally recognized for appearing in comedies.
When Annie is asking Rhodes to help them find Lillian, when Rhodes is standing at her car door he has what looks like a couple days worth of stubble on his face, but when he is back in his squad car, he is clean-shaven.
When Rhodes first has Annie pulled over doing the DUI test, a car's headlights can be seen coming up behind him, but it never passes them and disappears in the next shot.
The plane seen taking off to Las Vegas has two engines and appears to be a Boeing 767. However, when the plane makes an emergency landing in Wyoming, the plane seen landing is an L-1011 (three engines; the third mounted via S-duct in the tail).
Nervous Woman on Plane: I have to go to the bathroom but I heard about a woman who went to the bathroom on the plane - she got sucked into the toilet. Sucked right in.
What are the differences between the Theatrical Version and the Unrated Version?
A
The Unrated Version features approx. six and a half minutes of extended footage. It's not that surprising that the Unrated Version doesn't offer much more obscenities and revealing moments for the Theatrical Version already contains several crude jokes. The new material is narrowed down to scene extensions which also could have been removed from the Theatrical Version to streamline it a bit. A detailed comparison between both versions with pictures can be found here.
Q
What type of accent is Officer Rhodes speaking with?
A
Chris O'Dowd, who portrays Officer Rhodes, is from Ireland, (specifically, County Roscommon, in the northwest of Ireland) so we can assume his movie character is using his native Irish accent.
Q
Who sings the version of "Blister in the Sun" in this movie?
A
The artist is called 'Nouvelle Vague'. The complete list of songs can be found here with scene descriptions.