In fairness to them, it wasn't until I saw that episode for about the fourth time that I first noticed that black string. Once you're aware of it, it sticks out like a sore thumb.

It actually gets worse. In that same episode, near the end when Superman lands on the asteroid to set the timebomb, if you listen carefully you can hear birds chirping. Obviously the scene was shot outdoors somewhere on a Hollywood backlot.

I actually find such production cheapness sort of endearing. They did the best they could on a tight budget, and it usually worked out pretty well for its time.

@SixtiesHoldout said:

I actually find such production cheapness sort of endearing. They did the best they could on a tight budget, and it usually worked out pretty well for its time. Not unlike Ed Wood's Plan 9 from Outer Space.

I agree, and still feel nostalgia for this show and its times. But it's still sort of fun to spot little things like that.