Ravens

Overview
In certain personalized copies of Super Mario 64, usually ones that lean towards darker themes, it is possible for raven related anomalies to occur. The severity of these anomalies seems to be correlated with the degree of personalization the copy has been subjected to. What follows is a list of every reported anomaly, sorted from least severe to most severe.

List of Anomalies

 * 1) The most common one being that an unkindness of ravens occupies the roof of princess peach's castle. They usually can not be interacted with, although some reports state that they will fly away once the player approaches them.
 * 2) The second anomaly that players reported is that ravens will appear in courses, most commonly in Wet Dry World and Hazy Maze Cave.
 * 3) The next anomaly involves all swoops in the game being completely replaced by ravens, but also the ravens becoming extremely hostile. Players reported that the ravens were almost twice as fast as swoops and were able to kill the player with only one hit.

"Omen"
The final anomaly related to ravens that players have experienced so far has been nicknamed "Omen".

"Omen" resembles an anthropomorphic Raven, more than twice the size as Mario, that suddenly appears either in the distance or can be seen from the corner of one's eye before vanishing in the matter of a split second. Some players also reported that it was sighted standing right behind Mario while adjusting the camera, before vanishing on sight. It is said to wear either a black robe, a black coat or a black business suit.

Curiously, all the players that reported on "Omen" said they stopped playing the game right after. Some of them went on to claim they felt "cursed" or "haunted", this however can obviously not be verified and might just be an eleborate and coordinated "trolling" effort.

Update: Newer reports mention "Omen" and even the ravens possessing the ability to mimic human speech. Most reports describe the content of their speeches as nonsensical, absurd and yet unsettling. It's not yet known how the A.I. could possibly generate audible human dialogue that can simply be heard while in proximity of these entities. The sound quality of these messages however is as one would expect it to be from a Nintendo 64 sound chip, and probably contributes a lot to their indecipherable and incoherent nature.