Continuity mistake: During Naomi and Jordan's water fight over Venice he extends his arms towards her waist and asks for a kiss. Angle cuts and he's away from her, arms lowered. Then she throws the glass of water at him.
Continuity mistake: When the marching band shows up in the office a woman twirls a baton and it falls off her hand. A shot later she is twirling it again.
Continuity mistake: When Jordan presents the Oakman logo and brand the paper he holds swaps hands between shots.
Continuity mistake: When Jordan eats with his future partners he tells them to sell him a pen. The hand he holds it with changes between shots.
Continuity mistake: When Jordan goes to his Long Island job his boss talks about two brothers and radars and raises his right arm. From the opposite angle it's lowered and he raises it again.
Continuity mistake: When Jordan's wife finds a classified in the paper he raises a mug and takes it to his lips. A shot later the mug is gone.
Continuity mistake: During Mark and Jordan's meal, the second time they do the chest thumping ritual, in the side angles Leo Di Caprio can't help sneer and tries hard not to burst out laughing. In the front shot he is suddenly very serious. This swaps back and forth between shots. This was due to the fact that the scene was improvised, as Matthew McConaughey once told: https://www.independent.co.uk/arts-entertainment/films/news/matthew-mcconaughey-interview-gold-wolf-of-wall-street-lunch-scene-chest-thumping-tune-film-a7557551.html.
Continuity mistake: During his first day in Wall St. Jordan's boss tells him to pick the "c*ck sucking phone" which Jordan does and puts to his ear. A shot later the phone is gone.
Continuity mistake: When Jordan is talking with the FBI and their lawyers, there is a box on the table that moves between shots.
Continuity mistake: When Jordan is talking with the FBI agent on his boat, the sun changes between shots.
Continuity mistake: In the yacht scene with the FBI guys, the yacht is alternately docked to its port side with the stern towards open water and with the stern against the dock. When the agents approach the boat, they come from the left side and there is no dock at the stern. When they leave and Jordan throws them bills, they go around the boat's stern via a dock that wasn't there in the first shot.
Answer: Naomi's boyfriend.