Much of the first act of "Lightyear" sees the space ranger attempting to reach hyperspeed, which will help him and his crew return to Earth after being stranded on a mysterious planet. The catch, however, is that every minute Buzz spends in space trying to make the leap equates to one year on the planet, meaning that everyone on the surface goes on to live life without him. Nevertheless, he believes in his mission and makes several attempts, as depicted in a lengthy montage. At one point during this montage, viewers can spot a yellow laugh canister from "Monsters, Inc" tucked away in the background.
As seen in "Monsters, Inc." and later in its 2013 prequel, "Monsters University," the bright-yellow canisters were originally used to store the screams of the children whom the Scarers at Monsters Incorporated would spook. The canisters were then brought to different areas in the factory, and the screams were converted into energy that helped power the city of Monstropolis. By the end, they learn that laughs are more powerful than screams and use larger canisters to collect laughter to fuel the city instead. Although the canister bears no connection to "Lightyear," it's a nice surprise to see it pop up in the film, one that is sure to give anyone who notices it a little chuckle.
