We tend to trust our eyes when we say things like “this passes the eye test” or “I’ll believe it when I see it.” But despite this, our eyes aren’t necessarily reliable all the time. Case in point: just try to get your head around the things you’re about to see.
“Picasso cubism in photography.”

It stands to reason that putting half a face with half a face would look like a whole face, but there’s something a tad unnerving about this one. Maybe it’s the fact that only one of the eyes has an eyebrow.
“My cat looks like she has three front paws.”

I’m quite familiar with this phenomenon. In my house, we chalk it up to our cat being a derp who stands weird, but other cat owners are free to put their own spin on it.
“My son, floating in a chair.”

It’s amazing what even a hint of shadow can do to your perception of a photo. Take away the shadow, and this pic wouldn’t be noteworthy at all. But with the shadow, it really looks like the baby’s floating.
“Catnibalism.”

It took me a moment to see that the kitty on the right was simply resting their chin and not, in fact, unhinging their jaw boa constrictor-style to try to swallow their friend whole. I’m glad it’s the former and not the latter.
“Hi Elmo?”

There’s something about Elmo’s default expression that really fits the way I feel when I’m woken up. Like, the sun is up, I’m awake, and things are fine…but they’re just barely fine, because I’d much rather still be sleeping.
“Took this photo while on a train. Check out the white jacket….bears a resemblance.”

It’s uncanny how much this jacket looks like a polar bear. The button as an eye is straightforward, but the various folds really look like a nose and mouth.
“An upside down picture of a hand looks like a nude man with pimple on his back.”

I promise you this photo isn’t NSFW, but it’s still more than a little bit weird to look at.
“These staircases lead to nowhere.”

These staircases had to lead to the second floor at one point, right? Otherwise it’s hard to fathom why they were built. Even if that is the case, why were they ever disconnected from the second floor?
“This brick wall looks like it was not rendered properly.”

In video games, designers will sometimes take shortcuts and make something fully two dimensional if it’s just in the background and doesn’t need to be in full 3D. I guess this technique is spreading to the real world.
“This building near me.”

Here’s another example of the same phenomenon. In this case, I think it’s just an old timey building with a false front, but it’s still a weird look when you approach things from the side.
“My cat defying physics to lick egg yolk off my plate.”

Hey, cat, why do you have to be so weird? If you were normal, you’d just jump up on the table and eat the egg yolk comfortably like a normal cat.
“Only one more head needed until I have my very own Cerberus…”

If you must have a cerberus in your house, I suppose it’s way nicer to have an incredibly frinedly version with one less head. They look like very good boys.
“Does this corgi look huge to anyone else?”

To answer OP’s question: yes, yes it does look huge. It’s also clearly escaping from its pen, and the prospect of a giant, escaping corgi makes me more than a little bit nervous.
“The window of my apartment.”

It’s really weird how the shadows here distort what you’re looking at. That thin vertical shadow makes it look like the Venetian blinds underneath it are on the outside of the window rather than the inside.
“Looks like his legs are in the cart.”

This brings me back to the glory days of Jackass . If there was an unattended shopping cart, you’d better believe some teenagers would get in and start launching it off things for no apparent reason.
“This tree looks like an upside down person.”

It’s better to look at this tree as an anatomically accurate depiction of an upside-down person. If you look at it solely as a tree, it’s actually a pretty freakin’ weird and ugly looking tree.
“The pool looks like it is missing a wall, and the path lines up nicely.”

Alright, I give up. I see there’s some element of reflection going on here, but it all looks a little too perfect. I’m pretty sure it doesn’t show a pool that’s missing a wall, but I’m not positive.
“Wood splinters that look like a city.”

Wood splinters are bound to look pretty much exactly like this, pretty much every time. But looking at things from a unique angle helps put a new spin on things. It looks like a jagged version of Manhattan.
“This cracked paint looks like elvish writing.”

Imagine discovering something like this in your childhood home. You’d be absolutely convinced that your home was part of J.R.R. Tolkien lore, and no one would be able to convince you otherwise.
“Three-handed lady.”

Let’s start out with a doozy. Usually, you can ascertain fairly quickly what’s going on in a given weird photo, but this one took me an extra few seconds. For what it’s worth, the “third hand” under the table is a reflection in a mirror.