Very astute. In the movie the Leonov seems to have some kind of "space brakes" (shutters that swing out to aid in a type of retro brakes. But I noticed that the main engines were the ones firing. I guess it is a sort of vectored thrust to produce the braking. (More like a maneuvering brake that the aerobraking needed for orbital insertion) In any case the mains were firing so that is why the flare. (Sounds like a load of cobblers I know, but actually true...lol)