The Troat
The rebels in 2053 knew that they had created a time machine, yet appear to have never tested it.
Mannix told Defoe to set it to 1890, and he did, even though Mannix appeared in 1889. How did Defoe know how to do this?
This would indicate that The Throat was a workable entity before Mannix intervened.
Why did the rebels of 2053 only use it after Mannix had passed through?
Surely they would have played it with before Mannix came along.