Several GTA 5 and Online Easter Eggs reference Red Dead Redemption in some way. Some are incredibly obvious, while others might be easily missable for some players. The Grand Theft Auto series references Red Dead Online since it's still part of the Red Dead universe. None of the following are ranked in any particular order.
This list contains five examples of Easter Eggs tied to Red Dead Redemption 1, 2, or Online just for fun. As long as the reference is apparent enough to connect that series with GTA 5 or Online, it's good enough to be featured below.
Note: This article is subjective and reflects the writer's opinions.
Five examples where GTA Easter Eggs referenced Red Dead Redemption
1) John Marston as a dad to the GTA Online protagonist
Players who start GTA Online will undergo a basic character menu where they can customize a few things about their protagonist. One interesting thing of note is the Heritage system, which allows gamers to choose a Mom and a Dad whose genetics will influence the protagonist's appearance.
John Marston is one of the possible fathers a player could choose. Astute gamers should know that John Marston was the protagonist of Red Dead Redemption. The above picture shows how he would look in the world of Grand Theft Auto. Note that the Heritage system doesn't affect anything apart from your protagonist's appearance in Grand Theft Auto Online.
2) John Marston T-Shirt
Some NPCs in Grand Theft Auto 5 can be seen wearing a red T-shirt with John Marston on it. It's the same character from the previous Red Dead Redemption-related Easter Egg, except this reference is visible in the single-player game. One notable appearance of a pedestrian wearing this shirt is in the mission, Daddy's Little Girl.
He can be seen in the above Tweet and is involved in the bicycle rental store that Jimmy and Michael De Santa visit. It's not a significant role, so some players could easily miss it. Other pedestrians may also be spotted wearing this shirt outside of this mission.
3) Treasure Hunt and Double-Action Revolver
This is technically a two-in-one bonus. In GTA Online, players can do an optional event known as a Treasure Hunt. This activity involves them reading an email from [email protected], likely a reference to Red Dead Redemption 2's Van der Linde gang. That's not all, for the Double-Action Revolver comes from that game.
The gun's appearance is essentially the same in both games. This Easter Egg is slightly more hidden than the previous one but still apparent to anybody who has some knowledge of both of Rockstar's hit series.
4) Nazar Speaks
Red Dead Redemption 2's Red Dead Online had a character known as Madam Nazar. She's a fortune teller who also occasionally buys wares from the player across several different locations in that game. Otherwise, she's a mysterious entity (especially with Red Dead Online not getting any updates from Rockstar Games anymore).
She technically has a role in GTA Online by the incredibly minor Nazar Speaks Arcade machine. This little minigame typically quotes areas or events from the Red Dead Redemption series. Nazar Speaks costs $315,000 to purchase for anybody seeking to insert some of these machines in their Arcade.
5) Pißwasser Commercial
Another amusing GTA 5 Easter Egg can be seen in the Pißwasser commercial. Some gamers might notice that horses are seen a few times in the commercial, along with other shots that don't seem to be from GTA 5 or Online. The reason is that some clips come from the Red Dead Redemption series.
Since the commercial is intended to be uber-patriotic, showing cowboys and horses wouldn't be absurd in this setting. Some GTA 5 players don't bother watching the in-game TV or commercials, making it easy to miss this Easter Egg.
There are several more Easter Eggs in the Grand Theft Auto series than listed here. Some could constantly be introduced in a future GTA Online weekly update or big DLC.