Information on the location
The invisible plane is Wonder Woman's venerable, though now seldom-used, mode of transport. Wonder Woman's first plane was a product of the Lansinarian Morphing Disk, gifted to her by the Lansinarians. The subterranean technology could transform into a number of transparent items, and both Diana and Hippolyta used it to create a plane during their tenures as Wonder Woman. The disc eventually lost sentience and became locked in plane shape. It was, however, nonfunctioning.
One year later, Batman provided Wonder Woman with a jet that had the latest in stealth technology. It was not as invisible as the Lansinarian technology, but still fit her purposes.
Appearance in the rap battle
This is the vehicle that Wonder Woman was briefly seen flying during Stevie Wonder's line, "As never knowing how stupid you look in your airplane!"