We see in the preceding episode ("Panic") that the SID have electrified the vents leading into their headquarters. A perfectly sensible idea, but why aren't they so wired in this episode?
So who did take the flare gun and explosives? Mark, presumably, but it's never explained why he did this other than as a contrived plot reason to make him look suspicious.
The Earthlings seem to have unbelievably extensive knowledge of the comings and goings of the SID operatives, knowing who retired and who took their place and who was in line for promotions.
There is a reference to a carnival operator who held the little people captive. No such carnival operator appeared in any preceding episode, nor has the audience ever seen such a sequence of events. This might be a reference to Brady in the upcoming episode "The Marionettes", but that episode had not occurred already in either on-air or production order, and it was written by a different author.
Steve and Dan seem awfully casual about moving camp, despite the fact they will have to leave behind the Spindrift, giving them almost no way to get back to Earth!
Barry drifts in and out throughout this episode, sometimes appearing and sometimes disappearing in group shots.
Swan talks about having captured Mark once before, and that Mark hated him. We've never seen Swan before or since.
Zoral undergoes a face-change: he is played by Donald "Red" Barry, although Stuart Margolin had previously played the character in question in "The Mechanical Man" earlier this season.
The magnet-trap uses the same "teleporter" prop from the immediately preceding episode in air order, from the episode "Panic."
Since when do magnets cause strong winds?
Despite claims in the episode "The Weird World" that the Giants have poor night vision, both Swan and Grayson have little trouble spotting and shooting at the Earthlings during nighttime scenes.
The people involved claim that Inspector Kobick has retired. In fact he is in one more episode after this (although that episode was produced earlier in the sequence).
50-year technology gap: The Giants have electric pencil sharpeners
Supposedly alien planet: the Giants know of and understand how curare poison works
Supposedly alien planet: the Giants once again have normal Earth names.
Fitzhugh: Mark is absolutely right. I was trying to get to the truth like a real friend.
Mark: With some friends you don't need enemies.
(channelling Scooby Doo)
Barker: And except for that little one in the vent it would have worked!
Author William L. Stuart wrote both this episode and "The Mechanical Man", which this episode refers back to.