Due to The Time Tunnel being abruptly canceled, the series seems to end with a cliffhanger. There was no "series finale" which would have shown the end of Doug & Tony's adventures and their return home. Since the episode ends with footage from reruns of past episodes (a common practice for Irwin Allen productions such as Lost in Space (1965) during summer break), many viewers and critics have interpreted the conclusion to be that Doug & Tony were stuck in an eternal loop of repeating their 30 filmed experiences for all time, a convenient metaphor for syndication. Viewers with upbeat preferences have pointed out that Doug and Tony's signals are reported to be very strong in this episode, and prefer to assume that after their adventure in the Town of Terror, the two men were retrieved safely to Project Tic Toc headquarters.
Even though the show ended with this episode, the plans for the proposed second season were to have Doug and Tony successfully come home. After the bugs were worked out they then would be able to move though time to fix any anomalies their travels might have caused or use it for various other purposes.
This episode takes place in Cliffport, Maine on September 10, 1978 and in Arizona in 1968.
One of the pieces of equipment in the alien's "advanced" laboratory is an EICO model 425 oscilloscope sitting atop a cabinet where Doug and Tony are locked in. These were sold as kits for the electronics hobbyist by the Electronic Instrument Corp. of Brooklyn, NY. This particular model was sold around 1949. Common uses were ham radio calibration, audio, video and radio servicing.
In wasn't uncommon for Irwin Allen to reuse props and alien costumes from one of his shows in one of his other series. Here the alien costume for the aliens were also used in The Phantom Family (1967) for the alien Lemnoc. What's interesting here is that these two episodes were originally aired one week apart, and presumably watched by the same audience who would have noticed the identical costumes.