Colonel Lochley tells Sheridan that G'Kar and Dr. Franklin are exploring "beyond the rim". This is a nod to the fact that both Andreas Katsulas and Richard Biggs passed away before 'The Lost Tales' was made.
Nearly all of the props and costumes from the original series had been lost or stolen. The only ones to remain were a StarFury cockpit and Tracy Scoggins' EarthForce uniform.
There was a third storyline in the original script involving Michael Garibaldi, Jerry Doyle's character from "Babylon 5 (1993)." Eventually it was decided that there should be only two segments, and since his was the most complicated visually and technically, it was postponed for a next time.
When Sheridan's ship drops out of quantumspace to pick up Prince Vintari, the nebula visible in the background appears identical to, and is probably intended to be, the Ring Nebula, which is visible from Earth in the constellation Lyra. Technically, the vivid colors, which are taken from widely available images of the nebula, are false-color renderings designed to differentiate the different elements in the nebula, and the nebula is not actually bright blue and orange to the naked eye as it is in this scene.
The film takes place in December 2271.