Brian's human version is a Caucasian man with black hair in the shape of the top of Brian's head, a giant nose in the shape of Brian's muzzle, a white sweater and the same collar as dog Brian's. The promotional poster image of human Brian shows him with white hair.
In the first universe they visit, chapels seem to exist despite the lack of Christianity.
Stewie says he'll blow Brian's mind like the steropticon did in 1910, misnaming the stereoscope for the stereopticon, a common mistake.
In the Ice Age universe, Brian presses the button with his tail, however, in the next universe Stewie is holding it again. This universe was a last-minute substitution. The '1980s Bullies' universe was intended in this place originally.
Universe where humans' and dogs' roles have been reversed
Family Guy universe
In the Japanese universe, the people of Quahog wear Edo-era clothing. Japanese Brian's collar contains the Kanji character of "dog".
In another of Stewie's homosexual moments, when they travel to a universe of half-naked men and Stewie says "Love it!" and Brian says "Hate it." Brian's dog habits are shown when when he and Stewie reverse it when they travel to a universe of fire hydrants.
In the universe where everyone has a happy head and a sad head, Happy Stewie is seen kissing Sad Stewie.
The song that plays while Sexy Meg walks down the street is Van Halen's "Drop Dead Legs".
In the Dog World, Lois is a cocker spaniel, Chris is a sheepdog, Meg is a bulldog, Stewie is a poodle, Joe is a Doberman pinscher and Tom Tucker is a mixed breed brown and yellow dog.
The subject of Walt Disney's antisemitism is brought up again. Walt used racial jokes in many of his cartoons much like Family Guy, and was very anti-union which he attributed to communism which most American businessmen attributed to Jews through the mid-20th century. However, Walt was not known personally for hatred towards any particular racial group.
In the Two-Headed Universes, while most characters Happy Head was on the right and the Sad Head was on the left, Stewie's heads were the other way around.
In the scene where Brian and Stewie see Meg, in the censored version Stewie says "If you saw Lois you would have to put your penis in a wheel chair." but in the uncensored version he says "If you saw Lois, your penis would shoot right off your body."
This episode was selected as the "Best freakin' Family Guy Episode" on BBC Three in May 2012.