About 7 minutes into the story, Robbie (Leslie Nielson) is on a small hill. as the camera pans up, it shoots a little too high and reveals the top edge of the "Sky" (an indoor stage)
The person listed as Robert Keith Jr. is Indeed Brian Keith of Family Affair fame.
This episode is available on DVD through Television Classics; PMB 421; 991-C Lomas Santa Fe Drive; Solana Beach, CA 92075. The DVD has three half hour episodes: Frankenstein , The Crystal Egg and Appointment on Mars.
This episode is available for viewing by appointment at the Museum of TV and Radio 25 W.52 Street NYC
Although the program credits list Redfield as Bart and Nielsen as Robbie, the reverse appears to be true in the program. Other credits are Production: George F. Foley; Producer is Mort Abrahams; production in co-operation with Science Fiction League of America and Richard H. Gordon. Rocket is by courtesy of the American Rocket Society and Reaction Motors. Set design is Robert Bright; Technical Director Arthur Mace, Director of Graphic Art is Arthur Rankin Jr.