In the opening scenes, as the baby is wheeled down the hospital corridor in the sealed incubator the actors accidentally lift the camera side of the incubator allowing germ-filled air to enter the incubator.
Todd swallows the eye from his Teddy bear. the parents run down to get Todd to cough up the plastic eye to save him from choking. the scene fades to black. there is no scene that actually shows them removing the plastic eye from the chamber, so Todd is free to swallow it again.
While the first scene is set in 1959 actor Robert Reed wears a wide leather wristwatch band (sometimes called a full cuff 'Bund' band) which was very popular in the 1970s but rarely seen in the 1950s.
The first scene is set in 1959 yet a later model car (possibly a 1965 Lincoln) is visible in a carport behind Dr. Gunther as he speaks to the parents.
John Travolta's character would not have been able to walk back into his bubble wearing his special suit after walking around outside in it. The suit would have contaminated the sterile environment.
A boy slips an unsterilized ten-dollar bill into Tod's bubble.
Tod Lubitch is assigned a "bubble" roommate, Roy Slater, who has not been outside or in contact with the outside world for months. However, when Slater jumps on his bed, the soles of his bare feet are filthy.