An occasional bite of dog food won't hurt your cat. But dog food is not a substitute for cat food. They do have many of the same ingredients. But cat food is specially formulated for a cat's needs, which include more protein as well as certain vitamins and fatty acids. A steady diet of dog food can cause your cat to be severely malnourished.
other stuff you should not feed your cat is here (though some are very obvious others are not so obvious)
https://pets.webmd.com/cats/ss/slidesho ... -never-eat