I recently flew a multi-airline itinerary that included DL segments and a segment on US (all on 006 ticket stock). When looking at the reservation in the mobile app., the US segment was shown with the correct flight number, but it was incorrectly shown as a DL flight. This also resulted in the app. pulling flight status information from a flight that didn't exist in my itinerary.

Android v2.3.3
Delta app. v1.5.2