1.The handheld game Groot is playing is called Defender, an '80s arcade game in which the player must defeat waves of invading aliens.
2.There's a blue Tobias Fünke visible in The Collector's museum.
3.This image of Tony Stark on the news is actually a photo of Robert Downey Jr. from the Spider-Man: Homecoming red carpet premiere.
4.Before sending Hulk back to Earth in Avengers: Infinity War, Heimdall says, "All-Father, let the dark magic flow through me one last time." This is a reference to what Loki says to Thor when he arrived on earth in the first Avengers movie.
5.Rocket seems to have a thing for limbs. In Guardians of the Galaxy he jokes that he needs some guy's prosthetic leg and in Avengers: Infinity War he asks Bucky, "How much?" for his new arm that Shuri built.
6.Rocket also has a thing for eyes. He mentions taking eyes in both Guardians of the Galaxy movies, and he gives an eye to Thor in Avengers: Infinity War.
7.The shirt Peter Parker is wearing as he hops off the school bus reads, "Lettuce, the taste of sadness."
8.The old flip phone Tony Stark has is the one Steve Rogers left for him at the end of Civil War in case he ever needed him.
9.In the post-credit scene, Nick Fury is driving an Infiniti QX50.
10.Red Skull was played by Ross Marquand, who also plays Aaron on The Walking Dead.
11.And Proxima Midnight is played by Carrie Coon, who also starred on The Leftovers — ironically, a TV series about a large portion of the population suddenly vanishing from Earth.
12.In the beginning of the movie Loki says, "We have a Hulk," the famous line Tony said to him in 2012's The Avengers.
13.And when Bruce Banner can't conjure out The Hulk, he says, "I'll do it myself," just like Thanos said in the Avengers: Age of Ultron post-credit scene.
14.The Hulk crashing Doctor Strange's place to warn him and Wong that Thanos is coming is much like in the Infinity Gauntlet comic, except it's the Silver Surfer who comes to inform him.
15.The snap by Thanos that kills half of the universe happens in the Infinity Gauntlet comic as well.
16.The scars from Doctor Strange's surgery were very visible on his hands when he gave Thanos the Time Stone.
17.Peter Parker (who has Spidey-sense) and Mantis (who has empathy powers), both realized something was wrong before disintegrating. Peter says, "Mr. Stark, I don't feel so good." and Mantis says, "Something is wrong."