That little triangle piece that fits in right in front of the side mirror on the driver's side is gone. I can't find anyone that can order it and I don't know where to get a replacement. Any where on the web I can get it?

 

Try carparts.com or ebay.

 

hmm only place is the dealer..... the next would be junk shop if they have lancer available

 

They don't have that part listed, but they must be able to order it.
https://www.mitsubishiparts.com/

What about your Dealer?