In one shot of the mushrooms sprouting out of the nabe, a mushroom crashes through a window, but it was drawn without a cap on it.
During the closing credits, Kôichi Kitamura is listed as being the voice of Upa (Rupa's great-grandfather). This is incorrect, Upa's voice was in fact performed by Ken'ichi Ogata, who also provided the voice for Ataru's father. Kitamura's actual role was that of Lum's great-grandfather.