For another, fullback Leonard Weaver left the game with an injured knee in the first half, and I have no idea how serious that injury might be. The Eagles are really counting on Weaver, so his injury is a significant concern.
The defense looked a little shoddy in the first half. A blown coverage in the defensive secondary led to a 74 yard touchdown pass by Peyton Manning, and the Colts marched right down the field and scored on their first possession, meaning that the Eagles were down 14-0 before they knew what happened to them.
The offense fumbled on its first possession, but McNabb did engineer a nice touchdown drive that led to a 28-yard touchdown pass to DeSean Jackson, who split a seam in the Colts' zone for a nice scoring play. That, at least, was most promising.
All things considered, it wasn't an impressive performance by the Eagles against a very good Colts team. There are plenty of reasons to be concerned.