Layouts for "Stupid Sidekick Union" were not done in America; it was shipped overseas after the storyboard stage.
Although Tom McGrath is credited as director for "Stupid Sidekick Union", it was actually Ron Hughart who directed it. The book "Sick Little Monkeys: The Unauthorized Ren & Stimpy Story" explains that Tom received the directorial credit as a reward for the importance in his storyboarding.
This is the first Season 5 episode.
Despite being the first episode in Season 5, this episode and "Stupid Sidekick Union" aired two weeks before the final episodes in Season 4 ("Superstitious Stimpy/Travelogue (1995)").
Ren and Stimpy's song, "Come Fry With Me," is an obvious parody of Frank Sinatra's big hit song, "Come Fly With Me".