10 Essential Star Trek: The Animated Series Episodes You Must See

They ended The Animated Series with a bang — a supernova, in fact. Whilst attempting to rescue an alien ship travelling at impossibly fast velocities ("on the order of warp 36" — beat that, Tom Paris!), the Enterprise is pulled through a nova into another universe where it's Opposite Day. Time flows in reverse, the stars are black dots, descendants are born before their ancestors, and hot snow probably falls up.

This is Star Trek, though, cartoon or not, so what the episode is really all about is the vicissitudes of age. Having reached "mandatory retirement age," and due to be fanfared under the carpet on Babel, Commodore Robert April, first captain of the Enterprise and now ambassador, is on board with wife Sarah. This obligation to leave the service is put into question when both begin to de-age with the rest of the crew in the alternate universe. In the real world, mandatory retirement is now generally unlawful in the US (as it is in the UK), but there are still exceptions such as for airline pilots and, notably in this case, diplomats.

The Counter-Clock Incident was also the first appearance of Robert April, whose ties to Trek go all the way back to its conception. In Gene Roddenberry's original 1964 pitch for the show "STAR TREK is…", it is April (with an 'M' as a middle initial) who is "skipper" of the "S.S. Yorktown," before this was changed to Pike then Kirk of the Enterprise.