I dunno, I still think that giant cornucopia monster thing looks pretty authentic, with the sparks shooting out of its mouth.
Well, to a youngster with age in the single digits, it was pretty darn terrifying!
I remember a scene, I don't recall which episode, of a female crewmember dying.
She changed colour in a most eerie fashion while making a creepy sound.
That one actually gave me nightmares as a kid.
I think 2001: A Space Odyssey is a better example of 60's special effects, and even it got things wrong plenty of times.
Often deliberately. The moving starfield behind Discovery was known to be scientifically incorrect, for example, but was shown for cinematic reasons to convey the impression of motion. This philosophy is still in force. Where an object is meant to be moving, it has to be depicted as moving relative to the background or something else.
Certainly. Often something can look, sound and feel 'wrong', even when it's factually more accurate than the wrong version. On the other hand, some of the errors were just plain errors.
Reality Is Unrealistic.(TV Tropes link, so browser narcotic warning.)