Corrected entry: In the reentry scene in the Command Module, the astronauts are sitting with their backs are against the Earth and the CM is decelerating. The condensed water droplets should be dropping towards the Earth not the opposite. In the movie, the droplets fly away from the Earth. (02:06:00)
Corrected entry: As the Apollo 13 Command, Service and Lunar Modules near the Earth they make a comment about "shallowing" and this is due to a "couple hundred pounds of moon rocks" that the crew failed to collect. In reality, this configuration (CM, SM and LM) does not exist on return to the earth as the LM descent stage is left on the moon and the ascent stage is jettisoned after the crew returns from the moons surface. They may be shallowing but it's not due to moon rocks, it's due to the LM (5000-10000 lbs).
Corrected entry: Mission Control in Houston calls up "B.P.C. Clear", meaning that the 'Boost Protective Cover' has been safely jettisoned during ascent. However, the call comes on screen before it is shown being jettisoned.
Corrected entry: In the television interview, when the expert is describing the tolerance requirements for re-entry angle, he asks the reader to imagine that the earth is a basketball and the moon is a softball, and that the two balls are 14 feet apart, which is about 16.8 times the diameter of a basketball. The distance from the earth to the moon is about 30.14 times the diameter of the earth. This means that the 14 feet should really have been about 25 feet. Finally, the expert says that the re-entry angle has to be accurate to within 2.5 degrees, which he says is like aiming for a target the thickness of a sheet of paper. 2.5 degrees at 30 feet is actually about 13.14 inches thick (even at 14 feet, 2.5 degrees is about 7.34 inches).
Corrected entry: When Marilyn has the nightmare about Jim's mission meeting disaster, the Capcom says, "We show S4B shutdown," and then a few seconds later says, "when you get in the LEM." This makes no sense, because S4B (Saturn 4B Booster) shutdown happens before the LEM is even docked (and days before anybody would actually get in the LEM). Granted, it's a dream, but Marilyn Lovell was actually fairly knowledgeable about the way lunar missions worked, and you'd think that if she could dream everything else correctly (the layout of the capsule, for instance), she (or the filmmakers) would get that detail correct.
Corrected entry: As the spacecraft nears Earth the men in Mission Control remark that its angle of approach continues to wander away from plan. They figure out that it's due to the absence of the originally planned mass of moon rocks. This is wrong in several ways. First, it could not wander off course while coasting due only to the vehicle mass. From the time of Galileo it's been known that objects fall with equal acceleration (at a given distance) regardless of mass. Indeed, if that were the reason then the mass difference would not just be a lack of moon rocks, but also the extra unplanned mass of the entire lunar module. The actual reason was simply the slow leaking of gases from the damaged vehicle, acting as a low thrust rocket motor pushing it sideways. (01:53:20)
Corrected entry: When the crew are on their way back to Earth, Fido states "Flight. We're still shallowing up a bit in the re-entry corridor. It's almost like they're under weight." After some discussion in Mission Control, the crew is advised "We gotta get the weight right. We were expecting you to be toting a couple of hundred pounds of moonrocks." The amount of propellant in the LEM (since they didn't land, or return to lunar orbit) plus the fact that the LEM still had the descent stage attached, which, if they had landed would have been left on the moon would have more than made up for the weight of the rocks they were supposed to be carrying. But far, far worse than that is the fact that how much they weigh makes no difference at all, as Commander David Scott proved on Apollo 15 when he showed that a hammer and a feather dropped at the same time on the moon land at the same exact instant proving Galileo's law of gravity, that all objects fall at the same speed regardless of mass. (01:53:30)
Corrected entry: Right before the command module begins reentry to Earth, a hurricane is on Earth. When the Apollo mission took place (April 11-17, 1970) there were no hurricanes, cyclones, or typhoons.
Corrected entry: When the astronauts are too shallow for re-entry because they are too light, it is mentioned they should have been carrying 200lbs of moon rock. Yet the lander portion of the lunar module, which is supposed to be left on the moon, is still attached to the ship all the way to jettison before re-entry, weighing far more than 200lb.
Corrected entry: When Lovell is imagining walking on the moon, he looks at the Earth, which is near the horizon. The Earth is far too large (or too close) in the shot, something he would have known as he had seen Earth from the moon on Apollo 8 while they orbited (and took that famous Earthrise photo).
Corrected entry: When Jim Lovell is talking to his son about landing on the moon, he says his moon landing will be "Better than Neil Armstrong; way better than Pete Conrad." In fact, while Armstrong did make a less-than-stellar landing (hampered by low fuel and a problem with his targeting computer), Pete Conrad's Apollo 12 landing was nearly perfect.
Corrected entry: The scene showing the astronauts thrust towards the forward panels, and then violently back into their 'couches' is meant to show the massive thrust from the ascent and second stage engines. In fact, this sequence is inaccurate: The earlier Mercury and Gemini rockets did indeed create this massive 10 to 15-G load momentarily upon the astronauts, but the Saturn V did no such thing. The Saturn V never exceeded more than 2 Gs during any portion of lift off or ascent, and was in fact referred to as the "old man's rocket" by astronauts in reference to its relatively mild G-loads during flight.
Corrected entry: Many times in the movie, the Capcom refers to the CM and LM by their individual call signs, "Odyssey" and "Aquarius." In real life, those call signs would only be used when the LM had separated from the CM for a lunar landing. While the two ships were docked, as they were in this case for the entire mission, the single call sign "Apollo 13" would be used instead.
Corrected entry: During liftoff, one of the five second stage engines fails. This is indicated by a shot of the control panel, and one of the five indicator lights is flashing with a buzzer going off loudly in time with the flashing light. In fact engine failures were indicated by having a light simply go out, and there was no buzzer. Director Ron Howard originally shot the scene accurately, having a light just turn off was visually uninteresting and did not convey the drama of an engine failure. After getting the OK from Astronaut and technical advisor Dave Scott, the more dramatic indication was used.
Corrected entry: At the beginning of the film Walter Cronkite is narrating "a mere 18 months after the tragedy of Apollo 1..." The Apollo 1 tragedy occurred 27 Jan 67, while the moon landing of Apollo 11 occurred 20 July 69. The two events are actually separated by a little less than 30 months.
Corrected entry: In the scenes at the Lovell's home, as the crew nears re-entry, the priest, (who is wearing Catholic priest clothes), is wearing a wedding ring. (02:07:01)
Corrected entry: When Engine 5 of the S-II booster fails, as Lovell is waiting for word from Houston, he stares at the abort handle. However, at that point, the escape tower had already been jettisoned, so turning the abort handle would not have done anything.
Corrected entry: In the shot of Fred and Mary Haise at the Apollo 11 lunar landing party Mary is obviously pregnant. Apollo 11 was nine months before Apollo 13 and Mary is supposedly 8 months pregnant at the launch of Apollo 13. She does not have a baby during Apollo 13 and even if she was pregnant during Apollo 11 it would not have showed yet.