In a recent Reddit post shared to r/Movies, site user u/Ben_Soundesign asked, "What's your favorite 'blink-and-you'll-miss-it' Easter egg or hidden detail in a film?" Here are some of the most-upvoted answers:
1."In Doctor No, James Bond stops and looks for a second at a painting displayed in the Doctor's lair. The painting is Goya's Portrait of the Duke of Wellington, which had famously been stolen in 1961 — implying, of course, that Doctor No was behind the theft."
2."In Groundhog Day, when Phil starts helping people, he tries to save the old man but is informed at the hospital that the old man died. In the background, you see the kid who falls out of the tree sitting in a wheelchair. Phil wasn't there to keep the kid from hitting the ground."
3."In the closing credits of Cloudy with a Chance of Meatballs, there is a montage of various cities around the world in ruins after the events of the film; each one is accompanied by a star swipe showing the cities looking clean and nice again. For London, the city is grey and overcast and sad-looking. After the star swipe, it looks exactly the same."