Shared with you
The movie makes no mention of a mid-course correction made while en route to the moon, which took the spacecraft off of a free return trajectory. After the explosion, a second correction was successfully made to put the spacecraft back on a free return trajectory. Without this correction, the astronauts still would have swung around the moon, but would have missed the earth on the return leg. Although a free return trajectory was agreed upon in the movie, the engine burn to accomplish this was not portrayed. The astronauts also made a four-minute engine burn after swinging around the moon to gain additional speed and to enable them to splash down in the Pacific Ocean. There is a brief reference to this in the movie, but this maneuver was not portrayed.
In a commentary track, Marilyn Lovell comments that Tom Hanks exactly portrays Jim Lovell's mannerisms and style of movement.
Bill Paxton, Tom Hanks and Kevin Bacon were all very proud of the fact that they weren't sick on the so-called Vomit Comet - the plane used to simulate zero gravity. The cameramen weren't so lucky.
In some scenes where the Earth can be seen from the windows of Apollo 13, it is one of the photos taken by Jim Lovell and Bill Anders on the Apollo 8 mission.
Jim Lovell wore his old Navy Captain's uniform in the scene where he greets the astronauts aboard the U.S.S. Iwo Jima. When Ron Howard asked Lovell if he'd like to be in the film as the ship's Admiral, Lovell agreed, but pointed out, "I retired as a Captain; a Captain I will be."