During Taika Waititi's recent Instagram live, he showed off a couple of pages from Thor: Love and Thunder's script. The script reportedly included a surprise reunion between Thor and Iron Man. The conversation between the two characters, as per the script, goes something like this:
Thor: You're back!
Tony: In the sack, baby!
Thor: But how? I saw you die.
Tony: Science. Also, Thanos is back.
Thor: Mother Frigga, no. So... we're assembling again?
Tony: Again, again. It's GO TIME. Everyone who died is coming back. And this time we're avenging even more than ever. From now on we'll be known as...The Avengers, via Screenrant.
Well, it seems like a practical joke as everyone knows that Robert Downey Jr.'s time with Marvel Cinematic Universe ended with Avengers: Endgame. The character received a perfect sendoff and it would ruin the memories if we get to see him back due to some creative liberty.
Iron Man Easter egg confirmed by Marvel:
While talking about Iron Man, Marvel Studios' recently confirmed an Easter egg that fans have been dwelling on for a very long time. In the Endgame, when all the superheroes get together are preparing to travel through the Quantum Realm, to go back in time and get all the Infinity Stones, we see them reach out with their fists in a circle, and, from above, it kinds of looks like Tony Stark's old arc reactor.
Several eagle-eyed fans caught on to it and we're sure that this is Iron Man's callback to the very first movie. Well, Marvel has now confirmed it was a conscious decision.
Other than this, there are several other Easter eggs in the movie — several callbacks to the previous superhero movies.
For instance, when Tony Stark and Steve Rogers goes back in time to get the stones and Pym particle, they see Tony's father and his driver - Jarvis, who would later become Tony's personal AI.