A bit dramatic on this movie "Apollo 18"

I really thought it was the real thing. Then I saw the film and it was a make believe film like you have mentioned. It was a very good film though and who knows the possibility of having aliens like those may really exist.

Yes, there never was an Apollo 18. There were plans for 3 or 4 more Apollo missions but the program was dropped by Nixon because of the cost. Despite the fact that the program was halted, they had already built many of the capsules and rockets for the program. For that reason, they were able to create the Skylab program and used 3 capsules and 4 rockets for that. (One rocket was used for Skylab itself.) The Skylab program was a big thing for the US because they gradually increased the time where men stayed in space which helped give data for later space stations. The initial Skylab mission also was key because the Skylab module was flawed and the astronauts had to correct those problems or the spacecraft would have to have been abandoned. The commander of that mission was Charles Conrad who was the third man on the moon. The third and final mission to Skylab parked the spacecraft in a higher orbit to save it for future. The shuttle was supposed to send astronauts to Skylab for additional missions. When Skylab's orbit began to fail, there were proposed missions to try to save it and there was talk of launching a second Skylab since they had a complete spare already built. Instead, they let the spacecraft re-enter the atmosphere and break up. There was one additional Apollo spacecraft and mission but that was used in the joint Apollo-Soyuz mission. Apollo 17 was therefore the last manned mission to the moon and the last man on the moon was Eugene Cernan, the commander of the mission.