Thanks to programs like Photoshop, our inner skeptic almost immediately screams "FAKE!" whenever we see a fantastical image on the internet. This dubiousness isn't anything new, as humans have been manipulating pictures since the early days of photography.
Prior to World War I, "tall tale" postcards allowed smaller agrarian communities across the United States to brag about their agricultural prowess. These postcards featured cut-and-paste scenes of tiny humans wrangling with Brobdingnagian onions, geoducks, rabbits, and squashes. These photos resemble something Monty Python's Terry Gilliam would've animated if he was extremely hungry. As the Wisconsin Historical Society explains of these images:
Since postcards eventually came to function as a surrogate for travel, the photographic images depicting a geographic location engendered a certain myth about that town or region, usually equating the land with an Arcadian utopia. These myths were often reaffirmed by the handwritten commentary on the reverse. In this way, postcard photographers frequently selected subjects that might further the pre-existing myth of a region - a myth which often directly contradicted reality. The most crafty photographers soon realized that this myth could be altered not only by manipulating the camera's gaze, but by physically manipulating the photographs themselves, exploiting their ostensibly naïve depictions. Accordingly, nowhere did these modified narrative images, or "tall-tale postcards" as they came to be called, become more prevalent than rural communities hoping to forge a national identity for themselves as a place of agrarian abundance.
To be fair to the photo manipulators, these scenes wouldn't be out of place in the biology textbooks of the day. It's like Night of the Lepus, old school!
For more on the tall tale postcards of the early 1900s, check out this collection at the Wisconsin Historical Society and this Flickr collection. And for more weirdness, see this collection of unsettling vintage postcards and some hilariously manipulated "spirit photos."