I remember seeing Godzilla movies in the theaters in the 50's or early 60's. And "Attack of the 50 foot Woman."
I remember fondly this Japanese SF I saw as a kid...they were being attacked by flying saucers and had to develop their own space ships and laser weapons to fight against them. Don't remember what it was called, but as a kid I thought the effects with the flying saucers were pretty cool. Saw that at a drive in, with countless other sf, horror and military movies. But most of them have left my memory as being not memoriable to a kid...
Children of the Damned stuck, Little Shop of Horrors stuck, Them (I think I remember seeing it at the theater - but I have seen it so many times, I'm not sure that's where the memory came from) 13 Ghosts - not sf (probably because of the 3-d glasses) and Cleopatra stuck.
And then little memory snippets. I seem to remember a number of British movies that I haven't seen since a child. One of them, some film that was implying nuclear energy was bad, had a scene where the leading man was talking to a little girl who liked insects. They were looking at a bug. She was saying something about how she knew that all insects weren't bugs, but she called them that anyway. Now why that scene would stick in my head and the rest not, is beyond me!