As a former Mormon, there are so many insane beliefs I could not list them all.
But for example

Bigfoot is the eternally cursed Cain son of Adam wandering the earth till Judgement day
Satan has power over water so swimming is a dangerous pass time for the devout
God lives on a planet orbiting the Star Kolob at the centre of the galaxy
There is a Mrs God
The Adam God Doctrine is both true and an abominable lie, depending on which prophet you believe, even though both are guided by God
That special underwear bought in the temple will not only protect your junk from Satan, but is bulletproof
Inter racial marriage should be punished by putting both partners to death
There is no such thing as homosexuality, just the choice to sin.