Hopefully this thread isn't too old to be resurrected for a similar issue, it came up in my googling as the most recent.

I have a reservation in United system right now showing hilariously wrong flight durations.

ADD-SEZ on ET is a 3hr 51min flight per the flight search results, but reservation shows it as 12hr 51min. Departure and arrival dates/times are correct.

The SEZ-ADD return flight is actually 3hr 28min, but the reservation shows it as 18hr 28min. For this one, it has the departure date and time correct. But more worryingly, the arrival is listed as being 1 day late (correct time, but the day after). It actually shows me arriving in ADD 22 hrs after my connecting flight back to North America leaves.

This reservation is an award, it all priced correctly and was just ticketed. The email has times correct.

Funny error to have, hopefully there are no issues down the line with an arrival date showing up incorrectly.