Actually, strangely I kind of agree with DMan here ...
Captain Planet had some obvious impacts, beyond the
entertainment value it
purported to have (if you'd ever seen it, you'd understand - boring, preachy, generally obnoxious).
However, my critique comes from a pretty different source: ecofeminism. Ecofeminists claim that shows such as Captain Planet glorify the idea of the "natural nature" being the wilderness or the jungle and discourages kids from understanding that the evironment is everywhere, including the street in front of their houses and their backyards. This allows people (and not just kids) to shirk their responsibility for their immediate surrouding evironment to look at the bigger picture, which is really less work.
Ecofeminists also claim that shows such as Captain Planet depict evironmentally destructive people as rich, cartoon-ish characters, with no connection to reality. Then, kids cannot see that maybe they themselves, or their parents or people in their neighborhoods are part of the problem.
Seems kind of that out there, I guess. However, I can kind of see what they are talking about ... shows such as these, that stereotype and limit evironmental knowledge really do nothing but make people feel like they're doing something, even though they are not.