After killing the second boss, and leaving the club, Nero gets into the SUV. The brake lights are on and as the view flips, he starts the car and leaves. The brakes lights would not be on if the SUV was not started before he even got in.
Nero gets hit with a tiny tranquilizer dart that punches through the glass of his sliding glass door. The glass alone would have altered the trajectory of the dart and the way the dart works, would have released its payload upon impact with the glass rendering it useless for Nero.
In his assault on the final compound, the only weapon Nero has is the engraved 1911M1A1 he took from the third compound cartel leader. This handgun has a 7 round magazine. Assuming another round already chambered, he has a maximum of eight rounds and no other magazine. Yet he fires nearly 30 rounds in the final assault.
In his assault on the third target's compound, Nero shoots his way past the first wave of defenders, but leaves three of them alive and armed, focusing solely on the next bunch of thugs between him and their boss. Nero was too well- trained to leave his back so seriously exposed to getting pinned between fire from both front and rear.