Flight Incheon International Airport departs from Seoul Incheon International Airport at 21:50 and arrives at Macau Macau International Airport at 00:35.
The flighttime is about 3h 45m. The distance travelled ("as the bird flies"): 1654 Km. So the average speed is roughly 441 Km.
There is an 1 hour time difference between Seoul and Macau