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: The 6th of May.
don_corleone