Mario and Spiderman show up with no warning in Diaries to try to stop Satan, but get instantly killed and are never mentioned again.
Shrek makes at least one appearance in every video from Origins onward, with his face often stretched out and calling Knuckles "Donkey." This is because Knuckle's character here is a parody of Eddie Murphy, who played Donkey, but he still shows up out of nowhere and leaves just as quick. Eventually Knuckles finally acknowledges his presence in Shopping Mall and Finale.
Batman popping up from nowhere to say "This is bad" in Origins.
When the S.S. Ikea sinks in Doom Ship, Sonic is suddenly joined by other characters Roger Craig Smith voiced (Captain America, Chris Redfield and Batman,) to comment on the destruction. Like Batman, they vanish.
Fandom Rivalry: With Steve's general fanbase, in a rather bizarre example. While there are a handful of people who enjoy both the Sonic Zombies series and Steve's other content, they're few and far in-between. Thus, fights occasionally break out between the general fanbase, who wished that Steve would focus on more original work and professional Sonic fan videos, and the Zombie fanbase who just wanted to see more Zombie videos. Steve cited this great schism within his fandom as one of the primary reasons for ending the series.
Pandering to the Base: The explanation for how Shadow and Knuckles are brought back into the series after they were supposedly Killed Off for Real, and how Eggman allows a clone of Cream to tagalong with him in Doom Ship.
" is sang and written by Douglas Robb from a band called "Hoobastank".