Why didn't Mufasa's ghost...

[withheld]

...tell Simba it was Scar who had killed him?

 

[The Disney Movie Review]

That's a great question. Definite plot hole. I would say my theory is that Mufasa was less interested in revenge and more interested in Simba fulfilling his potential. Even when he was alive, Mufasa knew Scar could be difficult and was a little evil. If Simba returns to take his place as King, he has to fight Scar anyway. So maybe Mufasa felt it didn't need to be said anyway.

 

[Frozenheart9]

It would of relieved Simba of guilt though