Harrison Ford filmed his scenes while he was filming the early scenes of The Fugitive (1993). This is the reason he has a beard.
In addition to being the only episode of the series with Harrison Ford as older Indy, this is the only episode to include John Williams' original Indiana Jones theme music. This music plays during the bookends featuring Ford.
During his brief appearances as the middle-aged Indiana Jones, Harrison Ford sports a beard. This is because he was filming The Fugitive (1993) at the time his scenes were shot, and he didn't have time to shave it off.
Conceived as two separate episodes entitled "Chicago, April 1920" and "Chicago, May 1920", Director Carl Schultz had already filmed interconnected bookends featuring George Hall as Old Indy, lecturing his grandson Spike and the members of Spike's band. This footage was deleted in favor of the new bookend starring Harrison Ford in an attempt to boost ratings and re-launch the series.
Harrison Ford's scenes were directed by Frank Marshall.