As others have posted, know your agency's P&P; also ASK a NURSING SUPERVISOR when in doubt. Having said that --- being on the floor is NOT normal, therefore 99 44/100% times I'd be doing the full incident report portocol (witnessed, unwitnessed, knees down, butt down, low bed, other dept, whatever...) Best to err on the safe side. My worst scenario would be one week from then, that lady would complain to her family 'that she fell in therapy and she hurts a lot more now and... The family goes ballistic because they weren't notified and there's no documentation and nobody (ie. the current staff, not the involved staff) knows nuttin'... I can see it already, the phone call to the Dept of Health!
Therapy could have called nursing to check her out. My paperwork isn't 23 pages, but it is usually multiple documents, assessments, statements, referrals, care plan, etc and includes xeroxed packet for the DON office. A lot of stuff but better to CYA.