Continuity mistake: During the alien's assault on the ship, one crewman is seen near the spaceship's stairs firing a weapon. However, the weapon is pointed at a forty-five to sixty degree angle - at this angle, he would hit the bottom of the ship, not the alien that is much farther out.
Continuity mistake: As Adams chews out the guards for allowing the alien onto the ship, he is fiddling with a pen. Cut to a closeup and the pen is on the table.
Continuity mistake: When Robby is aiming the blaster at Adams, Morbius tells him to aim between the eyes. In the shot on Adams, the tip of the blaster can be seen rising at the edge of the screen, but Robby is too far away for that to be possible.
Answer: Many of the sound effects use an electictronic instrument called a theremin which was invented in 1919. You may hear it used more musically in The Beach Boys song "Good Vibrations." The visual effects would have been animated composites as used in Star Wars and Ghostbusters.
Myridon