In the opening scene when the alien ship flies over the moon, we see a shot of the lunar Apollo 11 landing site. The scene shows the famous "Here men from the planet Earth first set foot upon the moon. July 1969, AD" plaque as being on the ground.

In the real Apollo 11 landing site, the plaque is bolted to the leg of the lunar lander base, and not on the ground.

Oops!