Hydrocele can it come from a slip and fall?

Yes. A hydrocele can be caused by trauma to the scrotum and testicle. It should be evaluated by your doctor or a urologist.
It can be if... Yes, it can be if a man sustained significant trauma to the scrotum, but fortunately, most of such men will recover well with no significant residual effect.
Possible ; unlikely. Traumatic hydroceles do occur, however these are almost invariably painful ; following a blow to scrotum. Hydroceles can also develop after torsion of appendix testis. Both such hydroceles tend to resolve spontaneously with time. Long-standing hydroceles are not related to trauma or 'slip', however are occasionally related to testis tumors ; are worth checking out by scrotal ulrasound.