Apple usually holds on tight to its product announcements, so the posting mistake is unusual for the company. The images show the iPads are similar in design to their predecessors and have the familiar iOS 8 interface.
The TouchID fingerprint sensor is one new feature revealed in the user guide. Otherwise, the images don't share many details about the features. The tablets have iSight and FaceTime cameras, volume buttons and headset jacks. The iPad Mini 3 also has a nano-SIM slot for mobile broadband connectivity.
The iPad Air 2 is expected to also get an upgrade to the A8 processor, which were introduced in the iPhone 6 and iPhone 6 Plus. The chip is faster and more power-efficient than the A7 chip.
The new iPads are expected to be announced at an event on Apple's Cupertino, California, campus starting at 10 a.m. PDT Thursday. The company is also expected to announce Mac computers and will talk about the OS X Yosemite OS.