Yes, the temperature disparity has always bothered me, as well. However, upon doing a bit of research (inspired by your post, Fred), I found this: https://en.wikipedia.org/wiki/Climate_of_Los_Angeles

It shows that every month in Los Angeles has a temperature difference between the Record High and Record Low of at least 60 degrees. Most of the highs are in the 100's and the lows are all 49 or below. This to me says that despite the unlikelihood, these wild temperature fluctuations (deliberate nod to "Troubled Water") are entirely plausible.

This is a very good question. A possible explanation: as the former waiter dude at the recovery site stated, "When they found him he was all puckered up." Perhaps being in the ocean for several days had caused the signs of rope damage to disappear.

Thanks to John, Pete and Fred for their remarks.

Yes, I thought as well about the things like heat and how he could escape and did not.

Plus the sea wearing away marks could be the case.
It is one of my fave episodes like "Suitable for Framing" and The great "Candidate for Crime" with the equally great villain "Jackie Cooper" who later starred in the "Superman films as the Daily Planets" editor.

Many thanks to all.
Kevin