I don't actually see any physical problems with this combo. But you might find it a bit overstimulating, with methylphenidate and kratom. You might want to leave the ritalin out, kratom is plenty euphoric on it's own, somewhat stimulating, and would presumably provide a good base for the trip if you're that way inclined (although I've never tried combining the two). Methylphenidate may be too short lived for the mushrooms and might leave you a bit rough around the edges when it wears off, unless you continue to redose. I can't personally imagine wanting to do this with mushrooms though, it would freak me out I think.