Viggo trivia
Crimson Tide (1995)
After Captain Ramsey Gene Hackman holds a gun to Weps's Viggo Mortensen head, he threatens to shoot a junior sailor, Crewman Ince Henry Mortensen instead. This was played by Viggo Mortensen's real life son Henry. Although never discussed in the film, and not likely not known to Captain Ramsey (he had to read the Crewman's name from his uniform), the father/son connection may have extended to the characters. Both Morgensens were listed in the credits with the last name of Ince.
http://www.imdb.com/title/tt0112740/trivia?item=tr2202846
His son was born in 1988 and was 6 at the time of filming, so that can't be his son. Could it have been his real life brother? He has two according to his bio.