I was curious and stumbled upon this and wanted to share with everyone. Go back in the bunker and use the console command tcl to go through the floor and right under the radio you'll see a door. Once you go through that door you can explore the Villa again and kill ghost people with all your weapons.
Edit: To go back to the mojave use the gate and say you want to go back to the mojave then use the console command activate on the gate.

^ Never mind I found a way. Look in my main post to see.
For some strange reason you can't go back to the Mojave after using the door. One thing to note for people wanting to do this you must not save in the Villa.

Can't you just go back the way you entered, like in Point Lookout?

The dlc is the same deal as operation anchorage, you play it once and you never go back.

If you're on the PC, you might as well just get the mod that lets you go back.

Or you need save it before back to the Mojave Wasteland(If you miss something).

They have a mod out already? I looked before and couldn't find it. Well this is just a temporary solution for people who haven't gotten the mod yet.

http://www.newvegasnexus.com/downloads/file.php?id=40567 they have a mod. I've tested it and it seems to work fine.

Thank you for the link to the mod!

If you can think of it, then there's mod of it.
God I love PC.

Snowy, you are so right!

The mod won't get you to the vault...but if you really want some gold just for fun, the ref ID and the prefix 03 will get it for ya.

Or found the cell id for the fountain and "player.moveto"