Manderley, are you referring to those curious green patches I've noticed in SINGIN' IN THE RAIN? Do you happen to know the backstory on that one? I've never seen this discussed elsewhere, but if ANYBODY knows, it'll be you.
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Incidentally, in the number in question in the photo, "Fated to be Mated" in SILK STOCKINGS, La Charisse actually wears TWO costumes, apparently because that skirt would have been too revealing in the concluding choreography, so in the last shot her skirt is suddenly a culotte.