#1 : Did you know The atomic bomb in Megaton is the same model used by U.S.A. to bomb Hiroshima in 1945
This was kinda shocking to me, I didn't know about this for a long time

#2 : Fallout 3 almost wasn't "Fallout 3" let me explain.
Before fallout 3 there was fallout 1 and 2 right? Well at the time Black Isle Studios owned the rights to the fallout series, they were the ones who started fallout 3 and had a different approach of making this game, it was going to be a 2D type game, but then started the downfall of Black Isle Studios, they had to file bankruptcy and closed most of their studios before they could put their dream to work. Shortly later, Bethesda bought up the rights to the Fallout series, giving them all publishing and development control over the future of the series. This led to the huge change in gameplay and style that we have become accustomed to.

#3 : The Truth Behind Vault 101
Everyone who plays fallout 3 knows all about vault 101, I mean its the place you are born (lol) anyways, The vault is just a test being run behind the scenes by Vault-Tec. Vault 101 was designed to test the effects of isolation on a community, seeing how that community may change through time.

#4 : Megaton NPC Easter Egg
On PC, if you open the console and enter the command "tcl", you will be able to pass through walls and fly, if you do this outside of Megaton and fly up to the platform above and talk to the npc up there he will ask you "How did you get up here?" Its quite funny because the devs knew that someone would go up there so they decided to do something funny

#5 : Prophet Child?
One of the references in Fallout 3 that most people would have completely missed comes right at the start of the game. In fact, it is one of the very first things you'll see in the game; the Lone Wanderer's date of birth. Born on the 13th of July, or 7/13, this is a direct reference to the Bible. Specifically, it refers to Micah 7:13, a passage that describes how the world will turn into a desolate shadow of its former self, based upon the deeds of those living on it. Considering how the war between American and China led to the destruction of the world in Fallout history, this is the perfect biblical quote to reference in a Fallout game. However, like a few others on this list, it is really easy to miss as it isn't really something you normally pay attention to. Instead, you are almost certainly going to be focused on getting into the character creator and then starting that actual game. The character creator, especially, is something that a lot of people take time and care to play around with. But on your next playthrough of the game, try to look out for this little easter egg!

Thanks for reading my Guide, if you liked it please leave a like and a comment and let me know if you learned anything. And if you didnt like something I said then please voice that too.