But they didn't have the FX capabilities in the late 1960s to
realistically portray Saturn, so they went with Jupiter, which
did not have a ring (or at least one visible like Saturn, but
they didn't know that until 1979).

In the novel version of 2001, Clarke made some very interesting
"predictions" about the Saturn system.

One of them was about the rings, where ACC describes them
as having multiple lines like the rings of a tree. At the time,
most astronomers assumed they were just a few large sections,
even though a few amateur astronomers noted the multiple
rings back to the 1940s - but they were dismissed as optical
illusions (maybe Lowell and his Martian canals scared the pros
off).

The other was the moon Iapetus, the one with the very dark
and light halves. Clarke had the second Monolith (TMA-2)
planted in a large black and white crater at the boundary
between the light and dark halves of the Moon.

When the Voyagers imaged Iapetus in the early 1980s, they
found a crater almost exactly as Clarke had described it. But
no Monolith as far as I know (anyone checked those Cassini
closeup images carefully?).

Here is a video of Clarke talking about Cassini's flyby of that
alien moon last September:

http://saturn.jpl.nasa.gov/multimedia/videos/video-details.cfm?videoID=160