Welcome Back, Kotter

Groucho Marx was to make a cameo appearance in the episode "Sadie Hawkins Day". The planned scene was Kotter doing his frequent impression of Marx, then Marx appearing with his reaction. But when the 86-year-old Marx arrived on the set, it was decided that he was too weak to perform and the scene was scrapped. Marx posed for publicity photos with the cast but they were never released due to his frail appearance. Six years after Groucho Marx died, Gabe Kaplan would portray him in a stage play, filmed as Groucho (1983).

Throughout out the series, it's clear that the actors/actresses portraying teenagers are actually in their 20s+. This is done as to not interfere with the schooling of real teenagers and to give the general viewing audience who are teenagers (or young people) themselves someone they can look up to.

Featured in The 28th Annual Primetime Emmy Awards (1976)