I found a transcription on Ancestry yesterday, where 2 children aged about 5 & 6 had parents who were apparently well into their 50s when the children were born. When I looked at the actual copy of the census page, the transcriber has put two dwellings down as one, ignoring the double slash lines which seem to be used to separate out different families. The children were actually living with governess, housekeeper, various maids, nannies etc. but no parents. They had totally different names to the people before them on the census and there doesn't seem to be any connection.
As they aren't my ancestors, and anyone searching for the children will still find them, I've not bothered to send a correction to Ancestry. Not sure how I'd do it anyway.
Lizzie