Visible crew/equipment: When the first deal goes wrong and the man with the chainsaw jumps out the window you can clearly see him land on a grey crash mat because it lifts up at the corners. (00:27:55)
Visible crew/equipment: Just before Tony gets shot at in the Babylon Club, there is a close up of his face. In the mirror behind him, you can see director Brian De Palma's head.
Visible crew/equipment: In the scene where Tony goes back to his mother's house to visit her and Gina, watch the bottom right corner of the screen, on one of the kitchen appliances. You will see a shadow moving through the area, but no-one in the scene is moving at this speed or direction.
Visible crew/equipment: When the camera pans down, at the scene of the Carlyle sign, the crew members can be seen moving the camera crane in the reflection of the last window.
Visible crew/equipment: When they are leaving the Porsche showroom/garage, the entire crew is perfectly visible in Michelle Pfeiffer's sunglasses.
Answer: It's unlikely a set up. Tony is supplied with money and guns to defend himself. If this was a setup, the toad would've had more details. He would've known Tony had backup with guns and they would've waited to ambush them. Also makes no sense for Omar to put himself at risk without a legitimate opportunity to make cash. Frank knew about the deal as he supplied the buy money. Omar seemed loyal to Frank. Why would he send some low level thugs to be set up losing his boss' money in the process? All he would do is lose trust and be suspected.
Omar was an informant. He wasn't loyal to anyone. Omar's driver is the one that suggested to send Tony to the Colombians. And I think Omar knew the Colombians were shady, and that's why he sent Tony. It was, in a sense, a setup.