It is an excellent scene and not a fantasy. We hear that the gaffer on Lancer is friends from Randy on Green Hornet, we then flashback to Green Hornet (which was shot in '66 or '67) and see why Cliff burned bridges with Randy.
As for the scene in question, I am aware that there is some cultural appropriation at play with Tarantino establishing the fighting prowess of his fictional white, male, cowboy hero at the expense of a real-life person of color who had to fight the systemic racism of mid-20th century Hollywood, but with that said the scene unto itself is not mocking Lee anymore than Inglourious Basterds mocked Winston Churchill. So it is somewhat problematic, but it is a funny scene, for better or worse, and Lee himself does not "lose" the fight, nor is that the only flavor of him. I got a lot out of small snippets of seeing him train Sharon Tate and Jay Sebring that made me understand there was a good person there...if underdeveloped.
