It's being reported in a couple different outlets that the injury John Cena suffered in his in-ring segment with the Wyatt Family is legitimate.
Erick Rowan grabbed Cena's leg and held it in one place as the weight of his body went in another as Cena was attacked by the group. Cena, to his credit, worked the rest of the segment and waved off trainers who approached the ring. The injury that is being discussed is a possible dislocation or hyperextension. They showed Cena being stretchered out, and stretchered into an ambulance to be seen at a local medical facility.
Michael Cole pointed out that Cena's knee was swollen, and he was being evaluated by trainers as well as taken to the local hospital.
Obviously, this is a big story that will continue to develop over the next couple days. We'll post major developments as needed.