Approach, Landing and Demise of the Beaver
The De Havilland DHC-2 Beaver used for the movie was never intended to be crashed; however, the producers were compelled to incorporate the crash into the movie and its plot.
The aircraft was leased to Agamemnon Films by owner Al Beaulieu. In the film, you can clearly see that the Beaver is descending at a high sink rate with an excessive forward speed component. The flare is too shallow and forward speed is too great as the Beaver's left float contacts first and the water's drag action slows the left float quickly as the right float just makes contact; then the plane hooks to the left, causes a side-load on the right float, which lifts the left side of the plane, hooks it to the right, then the right side lifts. The left wing impacts the water and its spar breaks as the plane then ends up on its nose, then falls on its back and begins to sink. Beaulieu was, of course, not happy.
That is why smoothwater landings are highly discouraged: because of the absence of waves or ripples, it is very difficult to judge height and gauge rate of descent.
Famous last words:
Basinger: "Are you sure you can land this thing?"
Mancuso: "Piece of cake".
As they emerge:
Basinger: "What did we hit??"
Mancuso: "We hit the (expletive) water!"