Was "Lost Horizon" ever released with an intermission? After the poor box office reults of Columbia Pictures "1776" I would doubt "Lost Horizon" ever had an intermission (it may have been planned as a Roadshow but by 1972 roadshows came to an end and it (along with "1776") were re-cut for general release only.
If the film was only released in Mono in 1973 - I can understand why SONY is issuing a mono print (this is MOD after all, they are not going to spend a lot of money re-creating a stereo sound track. Does Pioneer own the stereo sound track made for the laserdisc? Could that track even be used (it is almost 20 years old)
When Peter Hunt re-cut "1776" in 2002 the soundtrack was re-mixed in Stereo (the laserdisc tracks were not used)
Fankly we should be happy with this film on DVD since for the longest time SONY refused to release it. The screen shots look very good. But why advertise 5.1 sound if it is a mono film?