“On your left!”
Another common theme that the audience loves looking for in MCU films is inside jokes and references. Before the portals open up in Avengers: Endgame, Captain America receives a notification about the arrival of Sam Wilson (Falcon). He alerts the Captain by saying “On your left!”
This one-liner is a callback to Captain America and Falcon’s first meeting when the Captain runs around his comrade. Every time he passes Falcon, he lets him know by calling out “On your left!” Funny banter is what the MCU films are all about! That, and the storyline, of course.