My husband has had visual and audible hallucinations since soon after diagnosis. Apart from one that started several years before and has been quite consistent, that is he sees fruit flies and is convinced they are living up his nose. They seem to go in phases, he will have several every day for a while then all of a sudden they stop. We have had things like fires and snakes under the bed, people in the back garden, leprechauns hiding or running all around the house and encouraging him to be naughty( we lived in Ireland when he first had symptoms), the neighbours playing music in the middle of the night, me being attacked/covered in rashes or being seriously unwell, his foot pouring with blood and all kinds of things in the bed that shouldn't be there. at one time he would take his shoes off and throw them at the leprechauns to frighten them away.
We have worked out that some of these things are probably sparked off by waking up from dreams and thinking they were real. He can usually accept it if I tell him darling I think you were dreaming. Thankfully he is still able to understand reasoning most of the time so where I can I try to show and explain. With the fire under the bed I showed him that there wasn't any flames or smoke visible, got him to put his hand near where he though it was to feel there was no heat and asked if he could hear or smell anything he started laughing when he realised how absurd it was. Unfortunately that didn't work with the bright green snake, we had to take everything from under the bed and look inside before he was convinced - at least it didn't occur to him that it could have slithered away to another part of the house.
Sometimes I can get away with saying "I think your head is playing tricks on you again.