survive high falls, cancel landing animation, quickly put weapon away
press M (map button)

fly or jump forwards while falling
hold jump and forward and press M

getting into the ground and sliding through the gate
hold jump, forward and M

go through gates or doors
Animal transformation almost always works. Strafing through the corner of a thin gate is possible, but can take a long time.

duplicate potions
get hit while drinking

fly across the map
pause in the right moment of the walking animation

walk while in dialogue
Open the menu just as an NPC talks to you and load a previous save. Nobody can attack you or talk to you anymore. This is only useful for the very end as this cannot be canceled.