Robert E. Lee Clayton
1.) How could a 60-year old Irishman (let alone any man) in the 1880s be named "Robert R. Lee" Clayton as the famed Confederate general only made his reputation in the Civil War 20 years earlier and would have not been known at the time of the character's birth in the 1820s. That is, if the film is set in the 1880s. if it is set earlier, it is even MORE illogical. (I believe the film is set in the 1880 as the US-Canada border, a plot device in the film, was only enforced -- due to the US desire to control the movement of the native American/first nations population between British North America and the US -- after the time of Custer's last stand, that is, 1876).
2.) Why does his Irish accent disappear at the time of the shack-burning/impalement-murder of Cary?
3.) Why is Clayton wearing a Mother Hubbard and bonnet (a disguise) at night when he attacks the shack?
4.) Why does Clayton, sniffing the air (at least twice) as the shack burns and Cary tells him that Tom Logan didn't escape the holocaust, not respond to this clarly false statement (as he is not smelling burning flesh which he clearly is trying to sense).... That is, why does he relax enough to let Logan creep up on him and kill him? Why hasn't he been vigilant?