Map Glitch is a state where load transitions cannot complete, such as loading zones, void outs, or soft-resets. There are many ways to activate it, generally requiring text storage along with an interaction among the death cutscene, the place name cutscene, the pictobox, or a menu being open in general. The most useful interactions will generally be the ones that have control over Link while Map Glitch is active, or that can end Map Glitch by closing a textbox.
One use for Map Glitch is to help performing PROC_ROOM_SCENE Corruption.
The initial method of getting Map Glitch involved getting both Death Storage and a stored textbox on screen at the same time. Instead of a stored textbox, Text Cancel works too. The order in which you get the state doesn't matter, but in order to do it without cheats you must get the text on screen first, then get death storage by healing with the tingle tuner. When you are in both states at the same time, loading zones can't activate and thus this causes map glitch.
In this example below, it is done with Text Cancel by Kalle Demos cancelling playing a song out of a Wind Waker dive, then getting Death Storage and healing from the heart drop.
The upside of this method is that you can have control of Link while having Map Glitch active, and you can make loading zones go back to working properly by closing the textbox or cancelling Text Cancel (ie by cancelling a textbox).
Be at a quarter heart, have a stored KorL text up, and get storage again. Now drowning will store the drowning death animation, giving you map glitch until you clear the text.
Contrarely to the method above, you do not have control over Link. However you still have control over when to cancel Map Glitch by closing the textbox. The following two methods don't have this upside.
By pausing on the frame Link dies, noticeable by the noise Link makes as you pause, you will have Map Glitch until you unpause. This explains the softlock that would occur to runners when savewarping out of Leaf Hover when pausing on said frame.
Abusing Picto Transition Interacting, you can chain the transitions all the way from taking damage (which would usually take you out of the Picto) to until you actually die a damage source, giving Map Glitch until you transition screens again and let it complete normally.
Death Storage can be difficult to obtain in an RTA setting. Using the "Place Name" text present in some location introductory cutscenes can be used instead in a much simpler method paired with a couple interactions.
Get a stored textbox on screen, then store a cutscene that has a Place Name present. You will now have Map Glitch while having control over Link, and until you close the textbox, having all upsides at once.
Abusing Picto Transition Interacting, you can enter a Place Name cutscene and have Map Glitch till you transition again and let it complete normally. This is pretty limited.
Using Wind's Requiem Storage, you can time opening the Sea Chart Map menu right as you talk to an NPC. You will have Map Glitch until you close the menu again, so it isn't very useful.
While in death storage, any prompt bringing up the menu can't appear if they try to play, but instead get stored and will appear after the next loading zone. Because textboxes softlock death storage, this usually needs some way to get around them. There are 2 menu prompts that can be delayed with this.
Both of these Menu Prompt Delays temporarely get Map Glitch, but the Map Glitch is removed when the text before the menu prompt is cancelled.
This glitch is different but closely related, and involves the bomb house door text or the Cabana door text, which has the property that it doesn't disappear and replaces any text that pops up on screen until you reload the quadrant.
Store the bomb house or cabana text, get storage, and die while it is on screen. Enter Death Storage and then close the textbox using the sail.
The game will enter a state where it tries to load the text but can't because of Death Storage. This makes the text unable to unload and as such, if you leave the quadrant, the island will unload but not its actors. Other islands also can't load anymore. If you try to go back to Windfall/Private Oasis, the island will be unloaded but not its actors.
This can also be performed on Outset Island with Mesa's House text during the day: