OK,
I think I figured it out...
All of the Non Kilted members shown in the movie are those of the "hinted at" 10th Bn CEF.

All of those Kilted members shown are supposed to be members of the 16th Bn (Canadian Scottish) CEF....Now, why they decided to put them together in the same trench I guess we will never know...maybe like I said, just Hollywood dressing the scenes up a little, who knows...but that at least straightens things out. WOW who thought Hollywood could be so confusing....anyway...despite everything, there are some great scenes in there! Another good movie about the 10th cef is the new (about a year old) movie "Paschendale" which after watching it the other week, I remembered that there weren't any kilted members in the movie, which is what sparked this interest in me...
Cheers,
CHad