Like, woah.

Check this out.

Remember Dick Tracy's radio watch? When the writers of that time thought about futuristic inventions, they knew that communications would be so important that everyone would need to do it, from any location. Especially people like Dick, out fighting crime and hunting down bad guys. And what did people always have with them? Their watches.
It never occurred to them (I mean, how could it?) that people would ever stop wearing watches. Everyone, they must have assumed, would always need to know what time it is.
Now, of course, in the actual future, we look at our phones to find out the time. How crazy is that?