Desert Island Film.

[Iceglow]

Ok well if we're "silly" like Dak suggested I would pick:

Modern Times Forever (Stora Enso Building, Helsinki) is a 2011 film by Danish artists' group Superflex. It is currently the longest film ever made, lasting 240 hours (10 days). The film shows centuries of decay, compressed into the span of the film, marking Helsinki's Stora Enso building; the building it was originally screened in front of during an art festival.

Whilst watching this I would wade out in to the ocean and using a rope made over 3 days from my own body hair plucked with the pincer of a crab lassoo two turtles. I would imagine it would take me about 2 days of standing in the ocean perfectly still to get the turtles to come close enough. With the remaining 5 days I would build up my supplies, fish caught with my bare hands mixed with leaves from the local palm trees (not the tastiest I would imagine but they'd probably contain enough fluid in the sap to keep me going) on the 10th day I would gather my supplies, lash my turtles to my feet like powered ski's and sail away to safety on turtle power.

Edit: if I can only choose one film to watch knowing it's my last movie and I will die a slow death of dehydration afterwards?

Well then I'd have a difficult choice to make. A couple of close contenders would be:

Scott Pilgrim vs The World.
The Matrix
Lord of The Rings
Sky Blue
Eternal Sunshine of a Spotless Mind
Armageddon
Romeo Must Die
The Crow
Pulp Fiction
Taken
Aliens.