The alien device is a redress of Tiabo's communication unit used earlier in Forbidden World.
Putting John Robinson on trial in front of a galactic jury gives the show a basic excuse to show clips from previous episodes. But because these episodes are all from Season 1, they're all in black and white as the series wasn't filmed in color till Season 2.
The automated communication box was also in Tiabo's cave headquarters in Forbidden World.
The lethal forcefield that imprisons the crew is - laughably - obviously just clingfilm.