Blood Moon is the 37th-38th episode of Big City Greens. However, it is the 29th-30th episode in chronological order. It is the first half-hour episode, and it's a Halloween special.
On Halloween, a spooky Blood Moon rises and turns the Green's farm animals into a horde of zombie-like creatures. 
It is Halloween night and Gramma Alice warns everyone that the Blood Moon is upon them and that things will not be the same. The family fittingly disregards her warnings as they prepare for the night.
Alice has Bill lock up the animals in the garage while Cricket and Tilly happily announce their intent to get as much candy as they possibly can. Bill interjects that he will join them, but the kids turn him down. When they lived in the country, they had to drive from house to house and they would not get as much candy, but now that they live in Big City where the houses are bunched together, they do not need him. Bill begins feeling dejected by this as he tries to convince the kids to let him tag along. Gloria shows up to tell Cricket to not leave any bad jack-o'-lanterns at work, but is scared by him and faints, forcing Alice to drag her inside. Remy and Vasquez arrive, both dressed as hot dogs, with the former upset over the latter for wearing the same costume.
The blood moon suddenly arises and the farm animals begin going manic attacking everyone. Everyone rushes inside to hide from the animals as Gloria awakens to the madness. She hastily attempts to escape, but gets bitten and attacked by the farm animals outside and runs back in. To make Cricket happy, Bill decides to simulate trick or treating inside the house for him and Remy, much to Cricket's confusion and annoyance. Tilly and Alice are convinced that Gloria is "infected" and tie her up. Tilly wants to perform experiments on her while Alice want to kill her. Vasquez sneaks off and discovers that the animals did not escape, but were let out as everyone begins arguing.
The animals break through Cricket's secret entrance as they overtake the house. Cricket manages to find a flashlight to ward away the animals and everyone (except Gloria who is left tied up on the floor) escape into the basement. As they collect themselves, Bill accidentally reveals that he was the one who released the animals because he could not fathom spending Halloween without his kids and did not want to lose a moment with them. Everyone is furious with Bill due to his actions and they choose to quietly wait for the Blood Moon to go away which could take hours. Bill then realizes that they can still make it out due to one of the walls in the basement being made of pure dirt and everyone digs out of the ground to the surface.
As everyone sneaks away, a little trick or treater arrives at the door for candy and accidentally releases all the animals who then proceed to chase everyone into the apartment building next door. Everyone reaches the top and proceed to grab as much candy as they possibly can while the animals proceed to attack everyone. Remy and Vasquez make amends with Remy realizing that Vasquez always dressed up as a hot dog on Hallowen and they get trampled by the animals. The Greens cut through Brett's apartment where he is having his party (the same one Gloria was trying to attend) and the animals begin wrecking the place. As they get to the roof, Cricket sacrifices his candy to save Bill and they prepare to be devoured. However, before they can do so, the Blood Moon lifts and the animals return to normal.
Remy and Vasquez make up while Gloria reaches Brett's party battered and bruised. Cricket apologizes to Bill for not inviting him earlier and promises to include him every year on, under the condition he shouldn't try to scare them like that again which he accepts. The episode ends as the moon suddenly jump scares with Cricket's face on it shouting "Happy Halloween!"
Additional voices: Shane Houghton, Luke Lowe, Kari Wahlgren