McCay continued to produce animated films using cels. By 1921, he had completed six, though three were likely never shown commercially to audiences and have survived only in fragments: "The Centaurs", "Flip's Circus", and "Gertie on Tour". In 1921, he released three films based on "Dream of the Rarebit Fiend": "Bug Vaudeville", in which insects and other creepy-crawlies perform on stage; "The Pet", in which a creature with a bottomless appetite grows enormously and terrorizes the city in a way reminiscent of "King Kong"; and "The Flying House", in which a man attaches wings to his house to flee from debt. McCay's son Robert is credited with the animation on this last film, but Canemaker notes it is highly unlikely that a first-time animator could have produced such an accomplished piece of animation.