One of the Earthlings was drawn to resemble series creator David McCall.
The information in the original version of this was correct for its debut in 1978. The reason the outer planets are glossed over was because at this time not a whole lot was known about them - only Jupiter had been visited by a probe (Pioneer 10 in 1973), and Saturn wouldn't be visited until the next year (Pioneer 11, in 1979). The IAU would not reclassify Pluto as a dwarf planet for another 28 years after this video was released. When played in theaters following the point where Pluto was no longer considered a planet by the scientific community, the outdated lyrics that had it listed as one could be dealt with in two ways. One was for a character to interrupt the song for an explanation. The other is in produced versions; the lyrics near the opening are changed from "Nine planets large and small, parading by" to "Eight planets", and those following "And Pluto, little Pluto" were changed from "is the farthest planet from the sun" to "used to be a planet but now it's not."
Voted #8 on the top 25 all-time favorite "Schoolhouse Rock!" songs.