As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
JUST AFTER TAKEOFF AT 300 AGL THE RT CABIN EMERGENCY DOOR OUTER WINDOW (PN C3FS515-2) FELL OUT. THE ACFT RETURNED TO THE AIRFIELD WITHOUT FURTHER INCIDENT, A NEW WINDOW WAS INSTALLED. THE WINDOW WAS RETRIEVED BY GROUND CONTROL APPROX 6000 DOWN THE RUNWAY, THE WINDOW WAS IN PIECES BUT NO WEATHER STRIP OR FILLER STRIP WAS RECOVERED. THERE IS NO EXPLANATION AT THIS TIME AS TO WHY THIS WINDOW FELL OUT.