I had to check something out..... but I
think the fishing location in Scotland is the River Etive. Another possibility is the River Kinglass; both flow into Loch Etive just to the north of Oban.
I fished the Etive for a day more years ago than I care to remember, the scenery 'on location' looks familiar to me but I'm not 100% sure as it's been 26 years or so since I was there last. I didn't catch any Salmon that day
but did have a brace or two of Sea Trout.
Of the two, the Etive is more probable IMHO.
H