When I was revamping the code to create the list of the most common subdistrict names, I noticed that I accidentally included more subdistrict than the 7255 listed in the annual statistics from DOPA. These were subdistricts already abolished, or planned but not created ones. But even after that my code still found one subdistrict more, so I looked for which province was the problem - but found wrong subdistrict numbers in census data first which I will post on soon as well.
The E-Book with all the Muban names from DOPA includes statistics as well, and there the numbers matched with mine, except the one case I was looking for. This turned out to be in Pak Phanang district, Nakhon Si Thammarat province, which has 17 or 18 subdistricts. The only subdistrict which is suspicious is Pak Phanang (ตำบลปากพนัง) itself.
Yet there are some sources including this subdistrict and other which don't. The most authoritative should be the definition of the subdistrict boundaries in this district, published in the Royal Gazette in 2003. This only lists 17 subdistricts; however on the other hand the DOPA population statistics includes this subdistrict as part of the municipality Pak Phanang (เทศบาลเมืองปากพนัง). On ThaiTambon.com the code 801201 of this subdistrict is missing.
Other sources are maps, the map from amphoe.com shows no such subdistrict. Other maps do show it, for example Google Earth or MapGuideThailand. And since I did not know about these problems back then, the subdistrict map I created for Wikipedia also shows it.
So I am puzzled, since I find nothing on a subdistrict abolishment in the Gazette, but also don't believe in a mistake in the DOPA entity numbers.