MacRumors reports that iFixit has performed a teardown on the iPad mini 3, in the process revealing that, as expected with such a minor refresh, not much has changed about the smaller tablets innards, with the same display, A7 processor, camera, and Wi-Fi setup.
There is, however, one new part, a 65V10 NFC controller, which is made by NXP, and which has something to do with the Apple Pay feature. While you cannot make payments in stores using Apple Pay on your iPad mini 3 (only the iPhone 6 and iPhone 6 Plus have that facility), you can use it in various apps that use the system.
The only other really notable thing found during the teardown is that the home button brackets are fixed in using hot glue, making it more difficult to remove the home button for the purposes of carrying out repairs.
MacRumors adds that the location of the Touch ID cable also makes repairing the screen very difficult, as it can easily be accidentally cut when opening up the display. These two factors have caused iFixit to give the iPad mini 3 a repairability score of 2 out of 10.