An easter egg is a hidden surprise or trick that is like a cheat code, but without the code. They are small surprises programmers add to the game for players to uncover, much like candy eggs in a real-life Easter egg hunt. Many easter eggs are purely for entertainment. Some examples include hidden names or faces of programmers, references to other games, or messages for the player.
- Barrel Cannon - On the bottom of the Barrel Cannon trophy is the message "2L84ME" which stands for "too late for me" in leetspeak referring to the usual KO after being shot from a barrel. The message can also be seen on the Barrel Cannon itself during gameplay, by pausing and zooming in on the character who is holding it.
- Daisy's third eye - In earlier versions of Super Smash Bros. Melee, the Daisy trophy contains a mysterious 3rd eye hidden in her hair, on the back of her head. It was removed in later versions.
- Sleepy time - An easter egg exclusive to Event 39: Jigglypuff Live!, sleepy time will occur when the large screen in the background of Pokémon Stadium is centered on the player's Jigglypuff, and the player uses Jigglypuff's Sing attack. All three of the other Jigglypuffs will fall asleep, regardless of the distance from the player's Jigglypuff, for much longer than usual.
- Fox and Falco's Smash Taunt - By quickly alternating between left and right (Melee) or by quickly tapping down just once (Brawl) on the directional pad while playing as either Fox or Falco on the Venom or Corneria stages, the player can use a special taunt. A similar effect happens when Fox, Falco, or Wolf performs the trick on the Lylat Cruise stage in SSBB.
- In Melee, Metal Mario's trophy has a reflection of the Yoshi's Island stage on its surface.
- Also in Melee, Ganondorf's Trophies (when viewed under certain lighting) have glowing eyes.
- Snake's Codec Messages - Using a method on Shadow Moses Island similar to the Star Fox secret taunt, Solid Snake can contact his support team via codec and get information regarding his opponents.
- In Trophy Hoard mode in Brawl, in the background with presents, there is a black DS Lite in a present box on the left.
- In the Ice stage of Pokémon Stadium 2, there is a poster of a white kitten inside of the shack in the middle. It is thought to be Masahiro Sakurai's cat.
- When you play the music Peach dances to when she uses her Final Smash in slow motion, it sounds like the music in the Coin Heaven of Super Mario Bros. 3.
- The Metroid trophy in Melee has a hidden image on its shell. It seems to be a Ceres Station lab (where the Infant Metroid was kept) from Super Metroid. This implies that the trophy is representing the Infant Metroid.
- The calendar- on the ice stage in Pokémon Stadium 2, there appears to be a calendar in the door, but it only appears when looking for the cat or using a hacked camera.
- Mushroom Kingdom Blast Zone Warning: In the Melee and SSB stage "Mushroom Kingdom", if one pauses and turns the camera all the way to the right or left, a black wall with a saying "DANGER" on it can be seen, which is appropriate as those areas are past the side blast lines.
- Onett "Runaway 5" Warning Sign: In the Melee and Brawl stage "Eagleland: Onett", if the player stands just to the right of the blue house and pauses, zoom out to see the "Onett Message Board" to the right. It reads "Caution, A black van driven by this guy (seen in the picture right of the message) has been spotted driving recklessly through town. Be careful!".
- Onett style rice: Using a hacked camera, a bowl of rice can be seen behind a bush on the Onett stage in SSBB. It is unknown whether this is a reference.
- R.O.B.'s Base: In R.O.B.'s Grey Palette Swap (which is designed to look like his American design), the words on his base change from "Family Computer Robot" to "R.O.B. - Robotic Operating Buddy", which is the name that was used for the robot outside of Japan.
- Cardboard Box Trophy: In the Cardboard Box trophy in Brawl, if you change the camera angle you can actually see Snake inside the box.
- Teetering- an animation a character makes when they're standing just short of falling of a ledge, they make a cartoon-like "teetering" animation.