- "They didn't tell us anything about a flag. Why is it so important?"
- "Because it's the flag, man, you know, it's the f... it's the flag, it's... Tucker, you tell him why the flag is so important."
- "Well... it's... it's complicated. Uh... It's blue, we're blue."
- —Tucker in Head Noob in Charge
The Flag is a piece of inventory stationed inside Blood Gulch outposts 1-A and 1-B. It serves as a goal for both the Red and Blue Teams, as they try to capture it from the opposing teams' base. It also serves as a religious relic to the Battle Creek Grunts.
- Caboose: Church and Tucker give Caboose a fool's errand to guard their flag in Season 1. However, he gives the flag to Donut when he arrives, due to the fact the others told him to give the flag to a non-existing general when he arrived, which Caboose assumed was Donut.
- Donut: In The Rookies, Donut goes on a fool's errand to get 'elbow grease and headlight fluid' by Simmons and Grif. However, he mistakes Blue base as a store and only takes the flag as it didn't have what he wanted and didn't want to return empty handed. Donut then takes the flag to Red base and continues to hold it until Tex attacks them.
- Tex: After being hired by the Blues, Tex attacks Red base to reclaim their flag in Knock, knock. Who's there? Pain. Although she sends the flag back to Blue base, she is then captured by Sarge and Lopez. Whilst on a training exercise during her time at Freelancer, Tex used a flag as a weapon when fighting Agent Carolina. She then threw the flag at Carolina causing it to ricochet into a nearby simulation trooper, Tex then removes the flag from his body to win the game.
- Red Zealot: In The Best Laid Plans, the Zealot obtains the Blue Grunts flag and orders everyone to stop fighting so they can witness him. After giving a religious preach of the flag, all of the Blue Grunts attack the Zealot to reclaim their flag.
- Sarge: In Loading..., as Sarge gives a speech to his team, two Red flags appear behind him and someone begins to sing, much to the others confusion. In the Deja View PSA, Sarge takes the Blue Team's flag by using a jetpack.
- Carolina: During a training mission with the Blues and Reds, Carolina engages in a game of capture the flag against fellow agent Texas, deflecting a homemade flag being thrown by hitting it towards a Red Team simulation trooper.
- Ironically, despite the main objective of the 'Red vs. Blue' civil war is to protect and capture the flag, no one knows why the flags are important or the reason why they need to have them.
- Due to Caboose and Donut being sent on fool's errands in Season 1 by their teammates, Donut obtained the Blue Team's flag, leading to all events later in the series to occur. For example: the Blues attack Donut in an attempt to reclaim their flag, resulting in Church's first "death", resulting in Tex being sent to Blood Gulch before her "death", resulting in Doc being sent to Blood Gulch, and so on.
- When Tex reclaims the Blues' flag in Down, but not Out, the flag simply transports back to Blue base.
- Before dying in Heavy Metal, the Red Zealot states "[he] can see the flag. It's so... flappy."
- The blue flag has a bird over 2 combat knives crossing one another on a blue background, while the red flag has a cobra over a diamond on a red background. These symbols are sometimes used in Red vs. Blue merchandise from Rooster Teeth.
- Biff is impaled with the homemade flag, recalling how in Halo, the flag is an effective melee weapon and there's even an achievement for killing someone with it.