The Redskins scored the final three touchdowns of the match but it was still not enough to overturn a 26-point deficit as the Eagles ran out 33-27 winners in their opening match of the season.
Griffin attributed the defeat to uncharacteristic errors from members of his team, including himself, but insisted that they would get better once those mistakes are cut out.
"[We] had a serious case of the can't-get-rights. Penalties, hurting ourselves," Griffin told The AP.
"I don't throw picks, Alfred [Morris] doesn't fumble, and Kai [Forbath] doesn't miss field goals. All three of those happened tonight. So we'll get better, no doubt."
Griffin threw two touchdown passes on his return from a lengthy spell on the sidelines with a knee injury.