Supper Mario Broth
@MarioBrothBlog
Additional obscure Mario content for http://suppermariobroth.com. Now on Patreon: http://www.patreon.com/suppermariobroth
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While reading a sign in the Behind the Waterfall area in Super Mario 64 DS, moving the camera to the left reveals an object that can appear as a Snifit, a coin, a Bob-omb or even as a "Coin-omb" depending on the angle. Stepping away from the sign reveals the object never existed.
In Donkey Kong Bananza, Pauline will often point out a banana when Donkey Kong approaches it. Due to a quirk in the game's item noticing priority, it is possible for Pauline to shout "An apple!" when approaching a banana, appearing confused about the nature of the fruit.

The Mario Party box can very easily be mistaken for the Mario Party 3 box due to the large and prominent 3 on the Dice Block on the cover. As it turns out, not even Nintendo themselves are immune to this, as this mistake was made in an annoucement post for Mario Party 3 on NSO.

In Mario & Luigi: Superstar Saga, the Mushroom Kingdom undergoes hyperinflation, whereby their coins lose value at a rate of 10 trillion percent during the game. Surprisingly, this is still about 40,000 times less than the most extreme hyperinflation in real-life history.

The original Japanese version of Super Mario 64 contains exactly 64 ! Blocks. Whether this was a deliberate reference to the game's name or merely a serendipitous coincidence is unknown.

In Paper Mario: The Thousand-Year Door for Switch, characters blink even when looking away from the camera (visible in reflective surfaces). An exception is Peach. This creates the unintended impression that Peach doesn't actually need to blink and only does it for the camera.
In Super Mario 3D World + Bowser's Fury, crouch-walking against a switch will make Mario vibrate extremely rapidly while emitting a barrage of "ha", "hoo", and "hmm" soundbites.
The birds in Super Mario Sunshine do not have terribly intelligent AI. It is possible for a bird to fly into a wall, repeatedly try to change its flight pattern to avoid it, and still continue to fly into the same wall.
Experimental post: Obscure/Ominous Messages Iceberg I have compiled a collection of various text messages found in Mario games that appear bizarre or unsettling, using the iceberg chart format. Explanations for each entry are linked in the ALT text.

None of the many emails Mario receives in Paper Mario: The Thousand-Year Door are spam, despite that being a universal experience when using email. Unused text in the original Japanese version reveals that spam emails were in fact planned to be included during development.

The director of Mario Kart 64 once bragged in an interview that players could put down 100 bananas during a race without them unloading. However, that is not the truth. The bananas start unloading far before that, at about 60-70 dropped.

In Super Mario 64, Metal Mario is immune to nearly all damage from enemies, including enemies not normally encounterable with the Metal Cap. The only exception is the giant fish Bubba, who simply does not care and will eat Metal Mario anyway.
Due to the forced diagonal-down perspective in Paper Mario: The Thousand-Year Door, a trick is employed whereby Mario actually walks faster towards/away from the camera than alongside the camera to create the illusion of smooth movement from that angle in particular.
Super Mario RPG contains an unused scene in its code that is a duplicate of the Peach scenes from Booster Tower, but with its dialogue overwritten by the Count Down boss messages. The result is a scene that unintentionally appears cryptic or ominous.
In Super Mario Maker 2, the Dry Bones Shell has mysterious "fate-sealing" properties. As long as Mario wears it, the RNG is locked in place, so that events that should have an unpredictable outcome play out the exact same way every time.
At release, a glitch existed in Mario & Luigi: Brothership where Mario and Luigi could be "overwhelmed by gifts". If a fight dropped too many gifts, the prompt to open them would vanish and Mario and Luigi would be forced to look at them forever without being able to open them.
The 2005 print ad for Mario Party Advance is bafflingly inaccurate, with only 14% of art assets being from the actual game, and 50% of art assets depicting things that do not appear in the game at all. Below is a detailed breakdown.
