Justin Long's first scene shot in the film was his nude one when he has sex with Drew Barrymore on a dining room table.
Jason Sudeikis sports a mustache in the film as he was concurrently shooting another film that required him to have one. Hence, a scene was specially written where he explains to Justin Long and Charlie Day why he wears a mustache - to make the older women he is dating remember what it was like to be with men with facial hair in the 70s and 80s.
Justin Long and Drew Barrymore have previously dated twice, in 2007 and in 2009.
Christina Applegate was director Nanette Burstein's first choice for the part of Drew Barrymore's sister.
Oliver Jackson-Cohen's first movie. Although he can do a very convincing American accent, Nanette Burstein opted to have him speak in his natural British accent to make him more appealing.