According to a New York Times article on technical mistakes in the movie (and personal observation), the film shows the moon changing phases several times during Apollo 13's four-day journey. There should have been only one phase, a waning half-moon, since Apollo 13 was scheduled to land on the left side of the moon and landing was always planned for sunrise, so that long shadows could aid navigation. (Sunrise on the moon, of course, occurs only every 28 days.). The changing of the phases constantly is probably for a more dramatic effect and to show that this is going on within multiple days because if the audience sees something changing it will subconsciously help them split events up into separate
According to a New York Times article on technical mistakes in the movie (and personal observation), the film shows the moon changing phases several times during Apollo 13's four-day journey. There should have been only one phase, a waning half-moon, since Apollo 13 was scheduled to land on the left side of the moon and landing was always planned for sunrise, so that long shadows could aid navigation. (Sunrise on the moon, of course, occurs only every 28 days.). The changing of the phases constantly is probably for a more dramatic effect and to show that this is going on within multiple days because if the audience sees something changing it will subconsciously help them split events up into separate