When Simmonds is trying to break out of his casket, we can see two aliens in the background. At the end of the scene, one of the aliens turns his head, the other sits up, but they were supposed to be in suspended animation.
At the end of the episode, Zantor's wig falls off as he lays down.
In the alien ship, the floor markings denoting where the actors should stand are visible.
During the crash-landing of the alien ship, Alan's Eagle co-pilot disappears in one shot.
The door aboard Eagle 1 reads "Rescue Eagle 7".
The Eagle docks to the Kaldorian ship on the starboard side, but they enter through the port side.
When they board the Eagle on the launch pad, it is docked on it's starboard side, but it is entered through the port side.
As Alan's Eagle leaves the alien ship, the Eagle had already begun to move before the thrusters fired.
Koenig: Simmonds, we can't afford to waste our time on something scientifically impossible.
Simmonds: Impossible? The impossible takes just a little longer, that's all, Commander.
Simmonds: Koenig. I think I'd better come too.
Koenig: Commissioner, right now I need a doctor and a scientist out there. Not a politician.
Zantor: On Earth, you freeze food to keep it fresh, do you not?
Dr. Russell: Yes. We do here.
Zantor: But the flavor fades.
Dr. Russell: The problem's the same all over the universe.
Zantor: Exactly. The flavor of life itself is lost.
Simmonds: Look, Koenig, I ought to be the one to go. I mean, I have no place here on Alpha. No function.
Koenig: Believe me, Simmonds, if I could rig that computer, it would shout out your name. But you take your chance like the rest of them.