2 Mario Ones.

[retrolinkx]

In the original Super Mario Brothers, if the player finishes a level as the timer is on a 1, 3 or 6 on any level with a flagpole, fireworks will explode in the air depending on what time you finished the level, so if the player finished the level at 346, 6 fireworks would sound off.





If I remember correctly, this also happens in New Super Mario Bros, but I could be wrong.

In Super Smash Brother Melee, when the player is playing the adventure mode, on the first level (Mushroom Kingdom) the player finishes the level by crossing a checkered finish line, if the player finished with 2 seconds on the end of the clock, the next level will play a small cutscene in which Luigi will jump onto the castle instead of Mario and the player has to fight Luigi instead.





Play the video at 1:18 to see the player finish and the cutscene.

I remember these both while playing New Super Mario Bros 2, which is odd.