What is the rarest Tomy/Plarail/TrackMaster item you own?

It might be a consideration if it has still has the original packaging, product name sticker, and the 3 accessories: 2 blue dolls, yellow shop and yellow signal lights. Still not as rare as the other considerations I posted way above. I got that one very recently and thanks to that I was able to confirm that the actual manufacture date is 1972 from the ST mark.

I haven't seen the blue dolls before until very recently, I have seen green dolls but I don't know if there are yellow/white dolls from the white platform type.

To be honest I don't know whether the white platform has dolls or not, I haven't seen them before but I suspect it exists because there are holes in that platform where the dolls are supposed to be fitted in. It is a very big question mark for me.

Even in the black and white CM, there are dolls moving around the platform. Talking about doll moving mechanism...
 That is a prototype, so do we consider that as the rarest among all 1965-1969 Plarail?

No prototypes in the list. I think it is unfair to put them in because that is on the management level, not public level.
But if you want some existing prototypes that someone on a public level has, let me introduce you:
https://twitter.com/KRT6019/status/1274172115072106502
https://twitter.com/KRT6019/status/1280850099363442688

Yes I have seen them before in our communications channel. He could be one of the former staff, or some staff gave it to him for safekeeping.

I wouldn't consider these options above as candidates for our list though.

What about sets that have internal products different from what was advertised from the box illustration? Your EF-58でんききかんしゃふみきりセット is one of them.

That one is hard to tell. I'm not sure whether sets like these that have a 50% chance of manufactured as a normal product or a derivative version of the set, or maybe it was an error product...? But lets keep it simple and stick to only 1 version of that type of product.

Will error products be in or not? Might be unfair, but it is on a public level.