Capsule

The astronaut 'Guy Taylor" is suffering from severe Hypoxia (Oxygen starvation). Three of the main symptoms of this are confusion, disorientation and acute behavioral change. Brain function can become impaired making it difficult to pay attention, making irrational decisions with poor judgment. After consultation the production team decided to go with these traits of the illness for the character from the moment he wakes up after blacking out. Taking him out of the environment he would normally have complete control of during his test pilot days and throwing him into an environment with little to no oxygen and see his character change from the consummate professional to someone barely holding it together on to the edge of his life.

Hypoxia can also cause severe headaches and hallucinations, seeing and believing things are real that aren't there.

The Johnson Space Center (aka Houston Control) was opened for business in late 1963, nearly 5 years after the setting of the film. The control centers at Cape Canaveral, Florida or Langley, Virginia would have been the US contact points for any craft that was orbiting the Earth prior to 1963, as "Houston" did not exist.

The credits end with, "No astronauts were harmed in the making of this movie."