Which miracle are you referring to?
- This does appear to be a continuity error. "Let's Kill Hitler" establishes the events in the opening sequences of "The Impossible Astronaut" take place prior to April 22 when the Doctor dies, yet Miracle Day is said to have occurred in March and continued for several months. As a result Amy and Rory should be immortal (though this effect likely wore off when they left the influence of the morphic field and therefore wouldn't have continued when they arrived in 1969) and the Doctor himself might have been rendered immortal too. Certainly the Doctor would have been notified. I don't think there's any way out of rationalizing the error, unless Miracle Day takes place in a different timeline.