Mendes suffered a seizure and spent the night in hospital in Manchester.
Greater Manchester Police announced they had received a number of complaints regarding the incident, and said it would be í░liaising with the injured player, the clubs and the FA to review this matter and determine if any further action is required."
"There is no official criminal investigation but GMP is duty bound to investigate the complaints," it added.
Thatcher was booked by referee Dermot Gallagher, and under FA guidelines, referees are not allowed to upgrade yellow cards after a match. However, the FA announced on Thursday:
"We are looking at whether this may possibly be an exceptional case and what options may exist under our disciplinary regulations."