Just bizarre nobody bothered to pounce on that ball especially the Birds. I have to see the play again. Did an umpire motion it was incomplete so they quit on the play?
It looked like only the latter to me, but to be honest every time they replayed that my eyes we more fixed on the ball just laying there on the ground and a zebra eventually picking it up. The referee that did pick it up didn't motion anything. The others were out of the frame, so I can't speak to them.
The Eagles definitely assumed it was an incomplete pass though, you could tell by how they reacted by running toward the sideline bragging.
P.S. I, myself, assumed it was an incomplete pass as it happened in real time. It was difficult to notice the receiver taking that third step from the original camera angle.