As far as Norway goes -
the biggest surprise, I'd think, would be the level of material prosperity, and the relatively low percentage of people doing "real jobs" (as in anything that gets your hands dirty). Back in the 1950s there were still a lot more people barely making ends meet as small-time farmers, fishermen and farmer-fishermen. Most folks got no more than 7 years of education and nobody had any idea about all the oil underneath our bit of the North Sea. There was post-war rationing of many goods still; automobile sales were also rationed with waiting lists and so on.
Media overload. Television only had limited trial broadcasts here during the 1950s, and there was one single national radio channel. Telephones were on manually operated exchanges and were not found in every house (in fact there were still long waiting lists to get a phone line installed even in the late 1970s).
Ethnic diversity, at least in the urban areas (out in the boondocks you can still go for days in some places without seeing a non-white face). In the 1950s you'd not expect to see a black person in Oslo.
Religion, public perception of morality, etc. Back in the 1950s the Church was a thing to be reckoned with, and cohabitation outside of marriage was in fact illegal until 1972, as were homosexual acts (both of these were only sporadically prosecuted, mind you). We'd been fairly early on the women's suffrage front but equal rights were still rather far away -- married women were mostly expected to be housewives, many professions were barred to them, etc. These days we have full gay marriage (and most of the opponents of this have already gotten over themselves), and being born out of wedlock ain't no thing at all. (Marriage is still pretty popular but people tend to do it later than in earlier generations -- often waiting until they already have a kid or two.)
Informality. Norwegian has a formal form of address [1] but these days it's almost completely dead. Newspapers frequently refer to people such as the Prime Minister by first name only.
[1] Famously, in 1895-1896 the explorer Fridtjof Nansen was on an extended expedition in the Arctic with only one companion, Hjalmar Johansen; the two men had to share a sleeping bag for a year and a half, and barely made it back to civilization alive. About halfway through, Nansen suggested it might be time to drop the formal address; Johansen replied that he needed to think this over.