The time travel computers and control panels at the mansion were previously used in The Time Tunnel (1966), another Irwin Allen time-travel series.
Much of the long-shot footage of the Chicago Fire is actually tinted stock footage from In Old Chicago (1938).
The outdoor set of 1871 Chicago was actually the circa-1890 New York street set built for "Hello, Dolly!" (1969).
This was a pilot produced by Irwin Allen that wasn't picked up as a series.
Francine York said years later that casting Sam Groom and Tom Hallick as the leads was a huge mistake because they were just "freakin' boring, really boring."