The lunar excursion module (LEM) seen in several episodes up close, is in fact a real lunar module. It was originally scheduled to go to the Moon as part of the Apollo 18 flight; NASA budget cuts forced Apollo 18's cancellation, but the LEM was saved and eventually used in filming this miniseries. It is now enshrined in a museum. In some episodes, we can see a bus-like craft which takes the astronauts from NASA down to the pad at Cape Kennedy just prior to launch. This bus is also the real thing, which the real astronauts all used.
Several of the Houston flight controllers are played by actors reprising the same roles from the film Apollo 13 (1995).
In this series, the "White Room" - the small room attached to the Apollo landing gantry, which the crewmembers pass through on their way into the capsule - is the real thing. It was discovered in a forgotten NASA storage room, taken out and used in filming.
To simulate the low gravity on the moon the actors had large helium balloons attached to their space suits by long wires. The wires were removed digitally in post production.
The large setpiece in front of which Tom Hanks delivers his opening monologues depicts the sun god Apollo and his three horses that pull his chariot across the sky.