1968 action with 1978 hairdos and outfits?

Rating: 7/10 (4 April 2016)

Is it just me or this is an unpardonable goof? To the point that way into the action ( i.e the much too long scene of the wedding) I was wondering what Vietnam-war were they talking about in 1978?! I had to look on IMDb to find out the action was supposed to take place in 1968...
Nearly 40 years later, I find the only valuable part that remains of this film is the well-known scene of the Russian roulette between the prisoners. And the final one, between Mike and Nick. Where De Nro's contribution is major.
I don't find the whole rest of the film stood the test of time.