Also, not sure if you knew, but Hope van Dyne’s missing cat almost had a role in all of this too. Ant-Man and the Wasp‘s co-writers previously shared a story about that movie almost including a line about Hope losing her cat, because Marvel was going to set up something to continue into Endgame. So the writers figured Hope’s cat was going to be the one to do the rat’s job and free Scott Lang from the Quantum Realm, or something. However, after a couple of months, the Ant-Man and the Wasp writers were told to never mind about the cat line, ’cause Endgame was going in another direction.
Article source: https://www.cinemablend.com/news/2480300/one-avengers-endgame-character-that-surprisingly-needed-no-cgi