maybe you have some more information about The Keep. Is there a longer version or more of a director's cut available?
There is no "Director's Cut." Mann himself doesn't seem interested in reworking the film with any scenes or shots to incorporate. He said there might be some material on the film in his archives, but he's not sure. You can find a longer ending on YouTube than the one you saw on the Blu-ray:
https://www.youtube.com/watch?v=dMpDerTdnNYI read that Michael Mann is not satisfied with the version due to financial shortcuts and his vision was a much longer version of the film and that much material he shot has not made it to the final cut/theatrical version.
Visual effects specialist Wally Veevers died during post-production, after filming had wrapped on THE KEEP, so apparently some shots/scenes had to be abandoned or left incomplete, and other scenes/shots had to be reshot after Veevers' death. Mann said that the special effects work begun by Wally Veevers was never completed and that the film also suffered from script problems (according to Mann, his screenplay wasn't fully finished before filming). He said he needed more shooting time before the film's theatrical release, but the major company Paramount refused to give Mann more money after Wally Veevers' death to complete his work.
Filmed in Wales and at Shepperton Studios during the autumn of 1982, The Keep suffered numerous post-production problems, mainly the death of special effects supervisor Wally Veevers before he completed his work on the film. The film was also subject to significant editing troubles, as Mann's original director's cut was 210 minutes long, which its distributor, Paramount Pictures, required be cut to 120 minutes. After test screenings of the 120-minute version received unfavorable audience responses, the film was truncated to its final 96-minute cut, which was released theatrically in December 1983.Wikipedia:
https://en.wikipedia.org/wiki/The_Keep_(film)
