This is a pretty common occurrence for me (once every fortnight at least), I have a very sporadic sleep pattern thanks to years of shift work where I'll be up at 4am some days and noon at others.

I also taught myself to lucid dream when I was younger (maybe 10 or so years ago) which turned out to be a huge mistake as instead of assuming control of my environment, it begins attacking me (pretty much everyone looks at me like I've figured them out and begins trying to kill me). I managed to break my patterns so this doesn't happen so much anymore but occasionally I realise and once I escape the dream there's no way I'm going back to sleep that night.

As far as the hallucinations go, it's a mixed bag.

• Auditory - Most commonly hearing my name being called or hearing friends voices having conversations in the next room (even though I'm alone in the house). But also lots and lots of music, not necessarily full songs i (although if I know all the lyrics it can be) mostly chorus's, but very clear and distinct - I quite enjoy these. I also hear video game sound tracks a lot, lot's of title screen music.
• Visual (3D) - It may seem weird for me to split these up but hopefully it'll make sense once you've read it all. These differ drastically based on my envirnment and mainly how light it is. On a sunny day things mostly just get blurry and distorted, this mostly causes me to mentally check out and start day dreaming until something essentially jump scares me back into focus, sometimes this is me walking into traffic and other times just a pigeon flying infront of me, I've also had numerous times someone pulling their phone out of their pocket looking like they are pulling a knife on me, which can be pretty freaky.
  In darkness it's much, much worse. I see faces in every shadow, any LED looks like eyes, any shape in the dark is a person staring at me (stuff like coats or chairs ect) every window has someone stood outside, staring. Creepy as hell but they always stay where they are and I'm so used to it that it doesn't really bother me too much anymore, I'm still hyper aware of all of them but kinda contently on edge it that makes any semblance of sense.
• Visual (2D) - This side of it I actually kinda enjoy, I say 2D cause even though I see 3D stuff it's always on a surface (like how your TV screen is flat but showing 3D images). This happens on walls, windows, menus, pillows, literally anything with a pattern. Stuff I see; street art being animated (I live in a city of with a TONE of cool graffiti so walks can be nice when I can't sleep, provided it's light out), scenes from TV shows/movies, SO MUCH video game stuff (my character walking around in OSRS, a cuphead level, more recently an awesome game called Overcooked 2, you name it - if I've played it I've probably seen it). These hallucinations are pretty chilled out but if I'm seated and not careful I can pass out so quickly and they shift into being my actual dreams.
• Physical - These have definitely been the most unsettling and luckily do not happen very often, only when I'm incredibly tried. I've had rats running around under my bedsheets (I think they were rats, when I lifted the bedsheets I couldn't see anything). A black cat prowling around me and never breaking eye contact (this one was visual too), I love cats but that thing gives off an atmosphere like it's arived to judge me and collect my soul, very unsettling. I once was walking through some trees and suddenly had spider webs around me on all sides, kinda like it was one big dome-shaped web, when I pushed on it I remember it being really elastic but not at all unpleasant to touch, the spiders moved to my arm but I never really sensed any ill-intent from them, it was just a really fascinating experience.

So yeah that's it, I'm sure my expereinces vary to others but I hope this was informative for those of you who haven't experienced it and are curious.