Many fans were surprised that Bill Mumy and June Lockhart didn't share a scene together, in an obvious homage to their joint work on Lost in Space (1965). The reason is that the two storylines were shot on different days, and the actors never even crossed paths on the set.
J. Michael Straczynski wrote this episode while suffering from a severe flu and bronchitis. He has no memory of actually writing it.
In a short story written by executive producer J. Michael Straczynski, the home planet of the race that built the healing machine was finally discovered, 500 years after the events of Babylon 5.
The cracking sound when Londo's tentacle retracts is that of a leather bull-whip. Executive producer J. Michael Straczynski specifically ordered the bull-whip sound effect to audibly emphasize the idea of great length.
This takes place in September 2258.