I know of a couple of cases of very young children coming out with weird things. A 3 year old, very matter of fact-ly started talking about her daddy being VERY ANGRY! - and the house burning down. Since the daddy in question is super-chilled, the relative who was there - and very disconcerted! - said she was sure her daddy would never be angry like that.
‘Oh, not that daddy, I meant my other daddy, before.’ Equally matter of fact.
Even spookier was a friend’s grandson, taken with all the family to a site of Graeco-Roman antiquities where none of them had ever been before. The child, who was pre school and unable to read, so couldn’t possibly had read anything about it, said at once, ‘I used to live here!’ and started happily pointing out the remains of his house, and a friend’s house (he gave an appropriate Greek name for him, albeit a mite garbled) , and the cave where they used to hide, and the pool or bath where they used to splash or swim.
When they finally left, he said very contentedly, ‘ Thank you for bringing me home.’
Needless to say, all the family were seriously spooked!
In both cases the children had completely forgotten the incidents/memories once past 5 or so.