The scene where Stewie and Brian go to Dr. Hartman's is taken from the movie Boogie Nights.
One of the strippers at the club resembles Connie D'Amico, a girl who bullied Meg earlier in the series. It could be the same girl or just a re-used character design.
The barista is Jillian (Brian's old love) though she is not voiced by Drew Barrymore and sounds completely different.
Seamus' area code is (917) which is an area code for all five Burroughs of New York City. (Manhattan, Bronx, Brookyn, Queens and Staten Island) However, it should be (401) which is the area code for the entire state of Rhode Island, where the series takes place.
This episode is based on the movie Twenty Bucks (1993).