In season 1 we see the recurring scene of what would become Londo and G’Kar killing each other for the first time. In this scene G’Kar has just 1 eye and Londo is emperor.
Later on in season 3 we see the scene again in a different form as Sheridan and Delenn travel through time. I haven't got to it yet but it may be that we see this scene play out again in seasons 4 or 5.
was this scene reshot for later seasons or was it all filmed during season 1 filming and then different parts used in later seasons? I have tried watching the scenes and can't see any continuity errors (outfits, etc) but that doesn't prove it was all shot in season 1.