What I didn't realize until I saw the movie on DVD was that in the one minute scene at the pool, he's in three different shots in three different places (so much for continuity).
First, so he can be recognized, from his slide collection here are excerpts from a couple photos of him about the same time in Mexico, one with him swimming in the same pool at Hotel Caleta:
From the DVD, here he is in the background in the movie, first as Cantinflas as the boy are having the drinks poolside:
Then as the headwaiter and Cantinflas argue:
Not high resolution, but clearly him.
And here's a clearer view of him with a camera on the diving board as the waiter is pushed into the pool:
And I might as well show the full photos from above with my father. This is with his brother Alex in their stylish 1950's wear:
And at the the pool at Hotel Caletas:
I have no idea who the woman is, but there are enough photos of unknown women in his slides that I will likely have a later post entitled, "Who Are These Women That Accompanied My Father and Uncle to Mexico in the 1950's?"