There was some controversy surrounding "Up the Down Steroid" and the 2005 film The Ringer , as both feature the same plot: someone pretending to be disabled in order to compete in the Special Olympics.  The Ringer was written and filmed months before this episode was aired, although, The Ringer was not released to the public until after this episode aired. According to the episode's DVD audio commentary, series co-creators Trey Parker and Matt Stone did not think that they ripped off The Ringer , since the idea to them did not seem hard to come up with, and they did not even think it was big enough for a twenty-minute episode let alone a two-hour film.  In the opening scene, the boys are playing the same "Investigative Reports with Bill Kurtis " funtime game as they did in the season four episode " Cartman Joins NAMBLA ". 
Early versions of the character first appeared in Parker and Stone's two pre- South Park shorts, " The Spirit of Christmas " (1992 and 1995). In the first Spirit of Christmas short, the character resembling Kenny is unnamed, while the character resembling Cartman is named Kenny. The unnamed Kenny-like character also speaks unmuffled in the first short. Both of these characters get killed in the short. In the second Spirit of Christmas , a character with both Kenny's appearance and name appears and dies. Kenny's first South Park appearance within the series was alongside Kyle , Cartman and Stan in " Cartman Gets an Anal Probe ".