In addition to being the first movie to utilize Red's 8K camera, Guardians of the Galaxy Vol. 2 was also the first movie from within the MCU to break the fourth wall. The breaking of the fourth wall is a shift in reality in a movie when a character acknowledges the audience. The term gets its origins from the stage, where a standard theater has three walls with an imaginary fourth, which is where the audience is seated. Fans of 20th Century Fox's Deadpool will be immediately familiar as Wade Wilson addresses the audience frequently in the first installment and is expected to continue the tradition in the upcoming Deadpool 2.
Though Deadpool is in the Marvel comics universe, he is not involved in the MCU, so Guardians of the Galaxy Vol. 2 is officially the first Marvel Cinematic Universe movie to break that fourth wall in a very sly way. The reality questioning moment arrives during the opening scene where Baby Groot is grooving along to Electric Light Orchestra's "Mr. Blue Sky" while the rest of the gang are in the throes of battle with the Abilisk. Groot jumps on the back of a weird looking alien rodent for a short ride, which is when the moment comes.
After Groot lets go of the alien rodent, he tumbles across the ground and comes directly into the camera. Groot's tree fingers can audibly be heard making a "dink" noise on the camera, as pointed out by Movie Pilot, marking the first time that the fourth wall has been broken in an MCU movie. Many have not picked up on it since it rolls by so fast, but is indeed the first time that the MCU has addressed the audience.
Throughout Deadpool, Wade Wilson addresses the audience in a humorous and over the top way, which isn't exactly suitable for the seriousness that is often associated with the MCU, but Guardians of the Galaxy Vol. 2 pulls off the humor and seriousness in a very clever way. The upcoming Thor: Ragnarok looks to be infused with quite a bit of humor this time around, so who knows? Maybe we'll see a fourth wall break in the new Thor movie before he joins up with the Guardians in Avengers: Infinity War. Speaking of Infinity War, Josh Brolin who stars as the villainous Thanos also stars in the upcoming Deadpool 2 and was recently asked if his character, Cable, breaks down the fourth wall in the sequel, to which he coyly replied that he was not sure, but that the movie was "even funnier" than the first.
We'll have to wait and see the fourth wall trend is something that the MCU will continue, but it seems doubtful that we'll see any lighthearted fun like that in Avengers: Infinity War or Avengers 4. One thing is certain is that Deadpool 2 will have plenty of fourth wall breakdowns contained when it hits theaters next summer. To check Baby Groot breaking the fourth wall in Guardians of the Galaxy Vol. 2 at minute 2:41 mark in the video below.