I don’t have anything really to add to this, but I wanted to bring it up. You should just read this article here.
Short version: The Beatles put a picture of Dylan on the cover of Sgt Pepper’s Lonely Hearts Club Band, and so he put a picture of them on John Wesley Harding. Only you really really need to look for them.
They’re up here in the tree:
And they’re upside down:
And that’s that.
The men on the cover with Dylan, by the way, were Luxman and Purna Das, visiting South Asian musicians, and Charlie Joy, a local carpenter. Dylan is also wearing the same jacket he wore on the cover of Blonde on Blonde.