[[folder: Fridge Brilliance ]]

* Wondering why doesn't King Boo have his Jewel Crown in later games? Because Luigi sold it to buy his new mansion (even though the jewel is worth 1 COIN).
* Luigi doesn't get to the mansion until Mario's been captured. Player 1 lost a life, and now it's Player 2's turn.
* You learn from a diary entry in the study that one of the ghost twins is susceptible to cold. This is because planes weren't protected from the weather when they were first built by Orville and his brother.
* Music/{{Brentalfloss}} points out that it's weird that Mario is unable to escape the painting, considering that he could go in and out of paintings in ''VideoGame/SuperMario64''. This could simply be explained by assuming that the painting Mario was trapped in works differently from the paintings in ''64'', but even if it ''did'' work the same, there's another explanation. In ''64'', Mario can't exit a painting unless he gets a Star, or he dies. As far as we know, not only are there no Stars in there, but there is nothing that could kill Mario.


[[folder: Fridge Horror ]]

* And then there's the heart quotes. Most of these are harmless little tidbits of speech that the ghost is keeping to themself. But then there's Sue Pea. It's a hint at how to beat her, but think. What if that quote was her last words?
* To people who played ''VideoGame/PaperMario'', Luigi's cowardice seems weird. In that game, he was eager and adventurous. However, if you read his diary at one point, you can see he was already scared of ghosts. And the first game with Luigi's fearful personality? ''Luigi's Mansion'', where he has to travel through a haunted mansion. Luigi is ''traumatized''. [[ThereAreNoTherapists And nobody seems to be helping him]].
** [[CowardlyLion Yet somehow through all this traumatization]], [[CrowningMomentOfAwesome he took out an army of ghosts by himself]].
* There's those two ghost twin children who love to play hide and seek, nothing inherently wrong with that right? Well if you happen to find a diary in the study, reading an entry reveals that they both like to hide during the game, sometimes causing the game to go on for a very long time...oh dear.
* So WordOfGod is that Chauncey was actually born a ghost; the immediate assumption is that Lydia and Neville somehow had another baby after they died, removing the inherent horror in a ghost baby. But then... Being born a ghost could also mean that he's the result of a miscarriage, a stillbirth, or the result of Lydia dying while she was pregnant.
* It's believed by some that King Boo's [[spoiler:Bowser "mech"]] isn't a mech at all, but rather [[spoiler:Bowser's corpse, with the Koopa King having been killed by Mario in a previous game]].
* So, the portrait ghosts. Not only are they technically ''real'', albeit dead, people being trapped in paintings against their will (and not all of them are even trying to hurt you,) but: Have you ever gone to the gallery and noticed how they don't move inside the paintings like how Mario does in his painting? [[AndIMustScream They just stand still, forever.]]
* All the area 1 portrait ghosts plus Henry and Orville are members of the same family. That means something horrible must have happened to kill all five at the same time. It gets worse if you notice there is also an Uncle Grimley, Aunt Petunia and Nana who could also be related to this family.