Continuity mistake: Buddy is having some drinks with Gekko, after he says "It's a piece of cake" the filming crew is reflected on his sunglasses.
Continuity mistake: When Gekko says that Ollie is the best trader on the street, Bud turns his head to his right, but when the camera angle changes in the next frame Bud's head is turned to his left. (00:16:00)
Answer: It's probably just a movie inaccuracy. For whatever reason, probably technical, economical, or for artistic considerations, the scene could have been staged and shot during sunset rather than sunrise. Oftentimes, scenes are not actually filmed when and where they are supposedly set. Locations are often substituted for ones that are more private, more scenic, have easier physical access, are in a less expensive economic region (such as Canada), and so on.
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