Southland

The name of Terrell's wife (Yvette) was a shout-out to one of the hairstylists on the show, Yvette Shelton.

At the beginning and end of this episode Officer Ben Sherman is running both his bloodied hands under the water, and his hands were supposedly bloodied while he was beating up the pimp. However, Ben never throws a single punch with his left hand during the actual beating; every punch is with his right hand.

The scene that involved Crazy Man (portrayed by Kirk Bovill), John Cooper and Jessica Tang in front of the patrol car was completely improvised. Kirk started ranting random things, such as apple pie, soft hands, he can see me, etc., and Michael Cudlitz and Lucy Liu just followed along. Additionally, the people seen taking pictures on the street corner at Hollywood & Vine were real tourists -- not extras.

It is revealed in this episode that Sammy and Tammi named their son Nate as a tribute to his fallen partner, Nate Moretta.

The first assistant director of this episode, Milos Milicevic, guest-starred as the large man who is brutalizing Officer Jessica Tang in the YouTube video.

The drugs that John Cooper states to the admitting nurse that he is taking for his back pain are Vicodin, OxyContin and Percocet, which are all powerful and highly addictive opioid analgesics.

In police jargon, "failure drill" means two shots (double tap) to the chest and then one round to the head.

The dialogue between Lydia and Josie in the opening sequence mentions the name "Muro." This was a shout-out to Jimmy Muro, the show's director of photography.

This episode was dedicated to Captain Bill Eaton, who lost his battle to cancer on January 13, 2011. Over his near 22-year career with the LAPD, Captain Eaton was respected for his talents, ethics and leadership. He was a mentor and friend to many within the Department and the community.

The title of this episode ("Code 4") refers to the police scanner code that means "no further assistance needed."

During the briefing, the names of Officers Rokos and Lisco are mentioned by the watch commander. These characters were named as a shout-out to Will Rokos (co-producer) and Jonathan Lisco (co-executive producer).

The idea for the title of this episode came from a conversation Cheo Coker had with Det. Mario Cortez, who had worked with the LAPD gang unit prior to joining SWAT. Det. Cortez said dealing with gangs is like punching water, i.e, no matter how many times you punch a bowl of water, whatever indentation you make, the bowl is filled back up with the water. In essence, no matter how many arrests the police make, because the culture of the gangs exists, there's always someone else to take the place when a gang member is killed. Nothing will change until society in general changes.

The line spoken by John Cooper about the "sticky situation" was not in the script. The comment was an adlib from Michael Cudlitz.

The character of Aaron Stanley, portrayed by Brandon Fobbs, was named after Cheo Coker's best friend in middle school.

According to the writer of this episode, giving the character, Victor Cifuentes, the same name as Jimmy Smits' character in L.A. Law was purely coincidental.

When Sammy Bryant told Nate he might name his unborn child, Wayne, after his dad, this was a shout-out to Shawn's father, Wayne Hatosy.

Although credited, Regina King (Det. Lydia Adams) does not appear in this episode.

When Ben Sherman meets his sister for drinks, she tells him Olivia and Ward will be there. This is a continuity error: Olivia is his sister's name. The character played by Taylor Handley was introduced in "Unknown Trouble" as Wade (not Ward).

The title of this episode refers to the third phase of a rookie police officer's probationary period at which time the rookie is permitted to drive a patrol car unaccompanied by a training officer.

The book Shamika Cole was reading during the hospital scene near the end of the episode was "Beloved" by Toni Morrison.