In its original airing on Comedy Central the episode was presented in "Spooky Vision" which added images of Barbra Streisand to the sides of the frame. This was in response to Streisand who criticized the show after her portrayal in season one's Mecha-Streisand (1998). The episode occasionally aired in syndication without images of Streisand.
Whenever Cartman and his doppelganger are seen side by side, there is a visible line down the middle of the screen. This is a nod to the old film splicing effect that used to be done to make an actor play two roles and appear to be standing side by side. If the process was not done properly the splice line could be easily seen. Instances of this include Kenny being unevenly placed between the lines as well as other distortions done purposely.
In Mirror, Mirror (1967), an episode of the 1960's TV. series Star Trek, the Evil Spock from the parallel universe had a goatee while the Good Spock did not. Here, the Good Cartman from the parallel universe (who is supposed to be evil) has a goatee while the real (evil) Cartman does not.
While Cartman waits for the bus, the pedestrian sign shows a man and a Visitor holding hands.