1984

For the record, this movie (1984) was made in the year 1984 (more than likely deliberately) — the book 1984 was written/published in 1948 (mix around the last two digits, and that's how Orwell came up with the totalitarian year). There's only about 3 or 4 other nations in the book. I seem to recall there might have been other flags shown in the movie of the other nations — or perhaps I may have made up some flags when I first read the book, my memory's a bit hazy right now.
David Kendall, 21 December 1998

Oceania

There is no description of the flag of Oceania in the novel.
Stuart Notholt, 15 November 1995

INGSOC

In the 1984 film of the book, a flag of the ruling Party, INGSOC (English Socialism) does appear, however. If memory serves me right it is black with a red "V" for "Victory". Across the "V" are two hands, one white, one black, clasped in solidarity. Across the bottom is the word "INGSOC".
Stuart Notholt, 15 November 1995

The movie opens with a patriotic shot of the Ingsoc flag flying. I believe the symbolism of the flag is the new order under Big Brother rising out of the darkness of the past — I'm pretty sure it was explained in the book.
David Kendall, 21 December 1998

If you look closely at the Ingsoc symbol in the film version of Nineteen Eighty-Four, the darker clasped hand is actually an industrial glove. Therefore it can be taken that the other hand represents that of a farmer. The image then takes on an entirely new meaning, that old socialistic idea of the melding and cooperation of agriculture and industry that can clearly be seen in the Soviet Union's flag.
"BDeal84", 9 January 2002

Eurasia

The flag of Eurasia is briefly depicted in the movie. It had a star in the upper left corner, and a thin horizontal stripe running across the flag. There may have been other devices; you never get a clear look at it.
Bruce Tindall, 10 February 1996

Green?

Yellow?

Well, I appreciated James Gallagher's effort but I do not think that Eurasia's flag is like that:

In the movie, Eurasian flag's picture appears very shortly and the image is blur and incomplete. But we can notice that the star is bigger and is nearer to the hand. The background color is light and the darkest color is not black. Looking to the colors in a lack-and-white image, we are able to think about probable colors.
I agree with you that the hand is white, but the background is only a little darker, and may be yellow. The darkest color may be dark blue, dark green or, what looks to be more probable, red.
Well, if the flag is yellow, red and white, there are used exactly the most common colors for communist countries, just as we suppose to happen in a superstate probably originated in the Soviet Union. Finally, I could not see the horizontal or sloped stripe. I think that the flag has an elipsis, in the same color of the background. Don't you think so?