Looks to me like a small, flaming stick was poked in from just off-camera.  And since that portion of the face was all fake, all make-up, I assume a li'l stick with a li'l flame not penetrating very deep would have been -- relatively -- safe.

Reminds me of DRUMS ALONG THE MOHAWK which I just re-watched on TCM the other night.  During an Indian attack, we see a two-shot of Henry Fonda and Ward Bond.  Bond is not only struck by an arrow, live on-camera, it's a flaming arrow.  Quite a potent, and seemingly very real, effect.

If you want to know what God thinks of money, just look at the people he gave it to.                                                                                     Dorothy Parker