I don’t know if this is a known bug, but for flight AF345 from Montreal to Paris, which takes more than 5 hours, a lot of the flights are showing a duration of 1-2 hours, which is impossible.
The erroneous flight times are the total amount of time the flights were tracked, not the duration of the flight.
Don’t forget: “At least part of this flight occurs outside of FlightAware’s service area. Information on this page may be unreliable” is underneath each of the flight maps for a reason.