One of Carl Sagan's more obscure movie appearances is in a video tribute to the environmental holiday produced by Time Warner in 1990. The special mixes its message with entertaining cameos by a wide array of pop culture celebrities, from Christopher Lloyd reprising his role as Doctor Emmett Brown from the Back to the Future movies to Rodney Dangerfield showing that having eco-conscious date plans are the way to get some respect.
In one segment, Sagan appears in full Cosmos explainer mode, lecturing an attentive audience on the scientific basis for understanding global warming, ozone depletion, and acid rain. The script was written by Sagan and Ann Druyan themselves, and they also penned an appropriately Cosmos-like opening narration about Earth's place in the universe:
We have searched the skies for signals. Our spacecraft have explored dozens of exquisite worlds in the family of our sun. But as far as we've looked, there's only one place in the entire universe where the miracle of life exists: our own planet Earth. Life is so rare and precious. We must safeguard, protect, and cherish it.Sagan is also one of the scientific advisors listed in the credits.
(I've also posted a lengthier, but less Sagan-centric, take on the special on my personal blog.)