Remenants of the actual WW2 Heinkel still exist! :http://ktsorens.tihlde.org/flyvrak/grotli.html

The replica is a pretty convincing prop:

He-111 by Sigurd R, on Flickr

The trailer shows it to good advantage:

And some stills from the film:Still from “Into the White” – Shot during coordination of the burn by Soren_Haraldsted, on Flickr

SFX – Actor Rupert Grint on set of “Into the White” by Soren_Haraldsted, on Flickr