I've never understood how they were able to launch from the moon back towards Earth. Launching from the Earth requires massive infrastructure and huge rockets. Yes, the moon's gravity well is shallower, but still significant.
It's because the fundamental equation that relates a rocket's performance and the mass fuel it requires to orbital velocities is exponential. This makes it work out so that any chemical rocket leaving earth has to have the vast majority of its weight as fuel, where as a rocket leaving the moon only about half of its weight as fuel.
What's more, the entire lunar module and its fuel supply is dead weight as far as the earth launch is concerned, which makes the earth rocket and its fuel multiple all the bigger. Then there's the issue of bringing along enough fuel to slow down the craft into lunar orbit, and escaping lunar orbit back to earth. The lunar lander didn't need to handle any of that, either.