... in fact there was only one slide, a six-shot showing separate images of Earth, Mars, Jupiter, Saturn, Uranus and Neptune, iirc, taken by one of the Voyager probes as it left the solar system, looking back. These photos I expect were the topic of his book "Pale Blue Dot."
We were, at first, diasppointed that the "slide show," which had created some hope of seeing new images from the outer planets, was this bunch of mug shots. Then Sagan began riffing on the photo showing the Earth: "see photo number two? Everyone you have ever known lives or has lived there. Everyone you have ever loved or hated, everyone you ever feared or charmed or helped." Words to that effect. It was a wily master stroke.