I know where I’m going, I know who’s going with me, I know who I love, But the dear knows who I’ll marry.

That leaves Flash, Waterfall, Fly, and (not a HM, but needed in much the same way) Rock Smash for another HM slave.

The inventor of a time machine about to commit autoinfanticide in the past

Practical lighting can help sell the illusion that the film is a real situation.