[*] In Super Smash Bros Melee,
- a Pokémon out of a Pokéball will not appear twice in a row.
- Mr. Game & Watch's side-B (Judgement) will not show the same number twice in a sequence of 3 numbers. See here for more information. This behavior is the same in Brawl but it was removed in Smash 4.
- Mewtwo can be unlocked depending on time played, I think. And it accounts for all controllers plugged in. So if you have 4 controllers plugged in, you can shorten the time until Mewtwo is unlocked considerably. See here.
Something similar to the property of Judgement and/or the Pokeball: Peach's forward-smash is randomly selected out of a tennis racket (with more knockback), a pan (with more damage) and a golf club (more range). You cannot get the same one twice in a row, meaning that doing a forward-smash can make the desired weapon become a 50-50 chance rather than 1 in 3 (or impossible if you just used it). I do not know if this is constant throughout the series.
Something else this reminds me of: for both Ike's Erupt and Donkey Kong's Giant Punch, the attack power increases the longer you charge, except when fully charged, where it gets substantially weaker. Another interesting property is that the KO Upppercut is charged with 100% damage to Little Mac or 333% dealt by him.
In Home Alone 2 for NES, that warp (around 3 minute in the TAS) used was never mentioned anywhere else.
In Over the Hedge DS, some locked safes also act as switches, but once again, the hint markers never mention it.
In Telefang 2 games, they have somewhat unique dialogue if you were to bring Rex (starter Denjuu) to certain story checkpoints
In Nanashi no Game, one of the cartridges is this: https://www.youtube.com/watch?v=B-u8qYggqEo
The path with map I made: http://i.imgur.com/bMqFuOe.png
It is completely invisible and absolutely at no point in the game is it ever referenced. Also, cartridges 24-27 all require certain DS time to unlock.
These: http://tvtropes.org/pmwiki/pmwiki.php/Main/GuideDangIt
Edit:
In RuneScape, since there are weekly updates, the devs sometimes leave certain changes unmentioned. There's a list here.
Harry Potter Sorcerer's Stone easter egg: https://www.youtube.com/watch?v=4TPg40t4T-Y
In Diagon Alley, buy 30 boots. When when crossing the lake to Hogwarts, pause and unpause the game, and then you can shoot owls at the enemies there with "A" button.
