Actress Riley Dandy has a condition called anisocoria where the pupils are of different sizes. Her right pupil is constantly larger. This is clearly visible in the movie on close ups.
A couple times in the film Sidney counts, "One Alabama, two Alabama..." The typical way of counting is with Mississippi's as in, "One Mississippi, two Mississippi..." Writer/Director Michael Felker is from Alabama which is likely why this change was made.
The matching tattoos on their wrists is likely an Easter egg tribute to the 1973 sci-fi mini series 'World on a Wire'