Maggie's Play Doh is spelled "Play (annoyed grunt)". Annoyed grunt is what is in Simpson's scripts when Homer says "d'oh! " this is likely done for copyright reasons.
The opening Silly Simpsony is a takeoff on Walt Disney's Silly Symphonies (a series of music-based cartoons) an, in particular, Music Land (1955) which dramatized the conflict between classic music and jazz with anthropomorphic instruments.
In the opening "Silly Simpsony" segment, Kearney appears as a pink triple-necked heart-shaped guitar, which was a distinctive custom Ibenez guitar owned by Steve Vai.