I'll take the liberty of stretching the thread a wee bit.
This was the most influential sci-fi for me, but it wasn't a movie, it was a radio broacast: Journey into Space
First broadcast in 1953, in the UK it was the last radio programme to attract a bigger evening audience than television. It could even have served as a model for Star Trek (and 'Q' in particular). From Wiki:
Although Journey Into Space was primarily an entertaining science-fiction adventure, it often touched on deeper moral issues, many of which were very thought-provoking. A recurring theme throughout all three series was the lack of respect which humans often demonstrate towards the Earth and each other. At times, a non-human intelligence (such as the Time-Traveller or the Martian), being much older and more advanced than mankind, would rebuke the main characters for mankind's selfish and destructive tendencies.
In Operation Luna, a good example is the diary entry which Doc unintentionally writes while being influenced by the Time-Traveller on the Moon:
... We should never have come. Man has no right here, no right to carry the secrets of this planet back to Earth, back to terrestrial beings who can neither understand them nor appreciate them, and in consequence will only attempt to destroy them, rip them to pieces, tear them apart, as they have already begun to destroy their own planet ...
Another example is Mitch's speech while possessed by the Time-Traveller on the Moon:
... Why do you interrupt the peace of your sister planet? ... Already you are tearing your own planet to pieces, destroying it, and now you mean to do the same here ...
http://www.jeton.themoon.co.uk/http://en.wikipedia.org/wiki/Journey_Into_Space----
Wonderful stuff, even for a 4yr old.
