There was one major dialogue in the Avengers Infinity War movie that had been used by Doctor Strange, and this was more than simply a reference for MCU, and it had hinted at a plot for the sequel movie.
From the start, the Iron Man movie was the heart of the MCU and the character. Iron Man has led from the front with Steve Rogers/Captain America. Tony Stark had fought for himself for a short while, but since the battle of New York had taken place, Tony was aware of the competition that actually existed outside Earth.
Tony Stark then got out of the little cocoon, and he started evolving and got an idea of the bigpicture. While most of the people on the planet had been thinking about themselves, this hero was trying to come up with a few plans and strategies that could prevent the destruction of the Earth and all the people living in it.
Tony Stark is all ready to even sacrifice himself for a much greater good, and he also carries the entire weight of the world on his shoulders. This is the exact reason why it was crucial for him to not die in the Infinity War movie. The character, Doctor Strange did not believe in Tony Stark to start with, and he was adamant to protect the Time Stone even if it meant sacrificing Tony’s life.
Tony Stark was almost going to die at the hands of Thanos, but Doctor Strange then saved him as he had seen into the future where the Avengers won against Thanos, and they actually had to lose the first battle and also, Tony Stark was crucial for this victory. Doctor Strange had given Thanos the Time Stone, and he said to Tony, “we were in the End Game now.”
This may simply be a reference but Doctor Strange had used this phrase for a very reason, and he had stolen it from Tony Stark as he had said something very similar back in Avengers: Age of Ultron.
“A hostile alien army came charging in through a hole in space… we’re standing 300 feet below it. We’re the Avengers. We can bust arms dealers all the live-long day, but… that up there? That’s the end game. How were you guys planning on beating that?”
Tony Stark had meant that these aliens living outside of Earth to be the ultimate End Game. Doctor Strange saw the future used and wanted to hint Tony about something. This is exactly why Tony Stark was alive.
Avengers 4 will be a huge Time Travel event, and a lot of references might come into play in the upcoming film.
The film comes out on May 3, 2019, and this is the Synopsis:
“A culmination of 22 interconnected films, the fourth installment of the Avengers saga will draw audiences to witness the turning point of this epic journey. Our beloved heroes will truly understand how fragile this reality is and the sacrifices that must be made to uphold it.”