5 by 5. WW2 military radio communications, particularly from pilots, could be iffy. A pilot might get a good strong signal from the airbase's powerful transmitter, while the base got a poor signal from the airplane's weak transmitter. So pilot and base would check with each other. 5 by 5 meant very strong signal with very clear sound. 1 by 1 meant very weak signal with a lot of noise.
In the original version of the scene in which Buffy and Faith meet again for the first time, Douglas Petrie had written Buffy attacking Faith first. Joss Whedon rejected this sequence because he felt it was "too unsympathetic to hit a girl who had just been in a coma."
The fire in the fireplace in the scene where Faith is spying on Buffy was a huge ordeal to produce. It was a real fire, and required a fire marshall on set as well as a certain number of fire extinguishers at the ready. Douglas Petrie felt as though the ordeal was worth it because the scene needed to feel homey and cozy.
When Faith walks through downtown Sunnydale she admires knives on display in the storefront window of Meyer Sports and Tackle, the same shop she and Buffy broke into in Bad Girls (1999).
The concept for the gadget Faith receives from the Mayor was based on gadgets designed by the American comic book artist Jack Kirby.