It's pretty obvious to me that the airplane and the boat were never
in the same lake together. Just a large rear-projection screen like
Hollywood used in the past, or a good old blue/green screen effect.

Notice the number of different camera angles used to film the boat
and the men in it.
1. A wide angle shot from some distance off the port side of the boat.
2. A close-up of the man in the bow shot from the stern of the boat
or even outside the boat near the stern.
3. A close-up of the man and the engine shot from the water on the
starboard side of the boat.

How, and to where did all of those other cameras disappear to?

Nope! just a series of video clips assembled in front of a blue screen.

I doubt it was a process shot. However, it was several takes, perhaps
shot on different days. The close-ups could have been filmed any time
and anywhere, and edited in. It's hard to tell from the highly
compressed clip whether the original was process, but there is no reason
for it to be. This kind of operation can be carried out quite safely.

Jose
--
The monkey turns the crank and thinks he's making the music.
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