Timeframe
Is it deliberately ambiguous?
Certain parts of the film such as some of the costumes (the jail uniform in particular seems very old) and the cars suggest that it's not set in the recent past i.e. in the last 20 years and yet the way they speak seems quite recent and the cop earns $30,000 a year so it can't be all that long ago.
I think it was probably intentional for it to be ambiguous and not set in any particular time or in 'Welcome to Colinwood time'. And I think it works. The whole film is a little quirky and this adds to the quirkyness. It was quite Cohen Brothers-esque.