I'll start it off as an example:
DMC1 why was there a fully functional (or partially functional) modern day (for DMC's timeline) air plane on Mallet Island....an island that has abandoned human life thousands of years ago...so it seems? Not only its neatly placed there like it was made there. Why did someone came there recently before Dante? Did demons construct it?......well could be since DMC is another universe apparently and Sparda had firearms (Luce and Ombra) before humans had firearm technology. (Ancient demons turning into electric guitars and demonic weapons that are transforming suitcase of hundreds of advanced firearms...Jesus were demons technologically advanced before humans).
There go ahead folks.
Actually, that's easy to answer. The Island didn't become abandoned until twenty years before the game started when Mundus was freed and went on a rampage. Plus, if you recall how you got the Grenade Launcher, military was there some time before Dante arrived.
what I want to know is how Dantes office changes I mean in all 4 games we see the interior but it changes from 1 floor to 2 floors in between games also the actual freaking sign in 1 Dante changes it to Devils Never Cry but in the anime and 4 it's back to Devil May Cry, 2 was the exception to this because they only showed the inside of the shop. Also what happens to all of Dantes Devil arms that he gets throughout the series?
That's also easy to answer. In DMC 3, the shop got totalled, so the interior changed into the one we saw in DMC 1. After Dante changed the name to Devils Never Cry, he changed it back (can't recall the reason). As for the Devil Arms... I can't really answer that one.