Continuity mistake: While Manny and Tony are working at the bar, before starting in the drug business, Tony has a towel over his right shoulder. Depending on the angle the towel covers part of his spine or it doesn't.
Continuity mistake: During the final shootout in Tony's mansion, the jungle-style magazines on Tony's M16 are constantly changing between shots, even when he's not reloading. This just goes to show how many takes were used for this last stand.
Continuity mistake: At Tony's mom's house, as Gina is following Tony outside, from inside the house the window shade is halfway down, but from the outside it is all the way up.
Continuity mistake: During the shot of Freedom Town there is a resident in a distinctive brown patterned shirt that keeps passing by in the background of the shot with Tony. When Rebinga enters the camp the same person in the brown shirt is entering the camp with Rebinga, only with a pronounced limp.
Continuity mistake: When Shadow is shot, in one shot he's touching his face, but in the very next shot he's touching the detonator on his lap.
Continuity mistake: As Tony chases Hector out of the hotel, a white handbag can be seen behind them on the pavement. Afterwards, once Tony shoots Hector, the bag is gone.
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.