Question

What remark of one of the two passengers makes us doubt about Mr Easton being a marshal

Answer 1

In the end of the lesson... one of the 2 passengers comments “Say— did you ever know an officer to handcuff a prisoner to his right hand??” This sentence makes us doubt whether Mr. Easton is the Marshall or the glum faced man ..
Hope this helps .. Cheers

Answer 2

The one of two man asked that Easton is very young for marshall job

That reason makes dout