When being advised about making a second attempt at re-entry, spacecraft commander Pruett says that they will do this by firing the RCS - the Reaction Control System. This refers to the 4 sets of thrusters (quads) fitted to the Service Module. He presumably suggests this as the engine from the SPS - the Service Propulsion System - had failed to ignite as planned on the first attempt. However the SPS engine has a thrust of 91 kN, and each of the RCS engines only has a thrust of 100 N. Even with an engine from each of the 4 quads firing together, their combined thrust would only be 400 N, less that 1/200 that of the SPS, and completely inadequate to bring the Apollo Command Module down.
Commander Pruett suggests shutting down two of the fuel cells to save electricity, saying that they can start them up again later. However the fuel cells do not use electricity - they produce it. They work by combining oxygen and hydrogen to produce electricity, and a little water. This is the reverse of electrolysis of water to produce oxygen and hydrogen. However shutting down the fuel cells is done by closing the reactant valves, and this is a one-way action as the valves cannot be re-opened except by technicians on the ground accessing the equipment.
As the Apollo spacecraft approaches the orbital laboratory, one of the crew reports that their speed is 50 feet per second. This means moving at a distance just over twice the length of the Apollo's Service Module every second. The view in the film is that the craft is moving considerably slower than this, closer to 5 feet per second, which is far more accurate.
The Earth as represented in the on-orbit shots is too small if the spacecraft is supposed to be in Low Earth Orbit (approx 200 miles) as would be expected for an orbital laboratory (and Voskhod) mission. The apparent altitude is more like 1000 miles.
During the countdown the Saturn V's Service Structure is seen in position at the launch pad, including when the Saturn V's stages are being pressurised. In fact the Service Structure was retracted from the pad the day before the launch.
At the start of the flight there are communications about docking with the LEM (lunar excursion module), but what the audience sees is just the command module (capsule and service module). If a LEM had been part of the mission we would also see the Saturn IVB stage, which carried the LEM.
The actual Apollo capsules were not white, but unpainted metal. Many find this confusing, as it is white then on the pad. The white shell covering the capsule is removed as part of the jettison of the emergency escape rocket system.
Powerful arc lights are seen being switched on in sequence and we see them lighting up the Vehicle Integration Building (VIB) which is recognisable by its 4 large doors, side by side. This is where the Titan boosters are assembled, one of which was to launch Dougherty in the XR7. However this takes place after the titan has already been seen being moved out the launch pad and so this sequence is superfluous, or should have been placed earlier in the film.
The Apollo Service Module's main engine used Aerozine 50 and Nitrogen Tetroxide - the same as in the Ascent Stage of the Lunar Module. A major reason for the choice was that they are hypergolic, meaning that they ignite on contact, and therefore do not require any form of ignition system, making its operation much simpler and effectively making a failure impossible. throughout the Apollo, Skylab and Apollo-Soyuz programs, there was never a single failure of the Service Propulsion System or the Lunar Module Ascent Stage..
When Keith announces the time for the launch through the eye of the hurricane, he says "We are go for launch at 22:31:06 local time". Moments later, the doctor privately tells Keith, "Of course, you know that by 22:31:06 the crew will be dead. There's not enough oxygen for three men to live that long". They then discuss whether two men can survive. Or even one. However, Keith does not even talk to astronauts about this situation until AFTER the launch, when the men should already be dead.
The astronauts are repeatedly shown releasing free-floating hand-held objects such as video cameras during their spacewalks. However, no loose untethered objects are ever allowed on spacewalks as the potential for them to float away and become hazardous objects is too great.
When Astronaut Lloyd does his "acrobatics" with the rocket pack, the sunlight is clearly hitting his right side. However, when he makes a 360 turn, the sunlight remains on the right side of his suit no matter what position he is in during the turn.
When Astronaut Lloyd does his "acrobatics" with the rocket pack, he ends his 360° rotation by pushing the joystick control in the same direction he used to start it, which should have made him rotate faster.