The last pull-away shot of the film is an homage to the scene by artist Edward Hopper's painting "Nighthawks." Edward was also the first name of the actor who originally played as 'The Equalizer.'
At the beginning of the movie, while getting ready for work, Bob dresses in slacks and a button-up shirt. He is wearing the same outfit while at work, but on his way home, when he gets off the bus, he is wearing blue jeans. Once he arrives at his apartment, he is wearing the slacks and button-up again.
When Masters is hiding out and hears the car alarm sound he prepares to go out. While doing so he opens the cylinder of the revolver to check his ammo. All of the primers have firing pin indentations meaning they have been expended. He then swings the cylinder shut before replacing the cartridges. This mend he has no bullets.
Robert McCall: [to Nicolai]
The men I killed, your men... I gave them a chance, they made their decision... Now I'm giving you the opportunity to make yours.