I think one would have to be morally obtuse to not comment on the racism in The Birth of a Nation or the Nazi propaganda in Triumph of the Will, but I think that's a bit different to implied Reaganism in Field of Dreams. A lot less insidious, to put it mildly, and therefore easily set to one side in favour of (to my mind) the film's undoubted merits.

Although the $20 thing does sound a little awkward in the way you argue the point here, I'm not sure I agree that Ray should have failed financially. Faith has its own reward, yes, but I think because God was specifically asking him to step out in faith financially by destroying his crop, it is fitting that he is rewarded for his obedience by not facing financial ruin (in addition to the catharsis with his father). But perhaps the money should have come in voluntarily, like in It's a Wonderful Life, by people donating as a means of saying thank you, rather than as an entrance fee.

Either way, it's a minor nit for me. :)