File with JPG extension acts like a GIF with a cat shooting a gun with heavy kickback

I recently came across this image which seems like a normal GIF:

Even imgur stores it as a GIF when I uploaded it here.

But when I saw the link, it was a JPEG image, unlike a GIF than what I had expected!

Here's the link: https://fbcdn-sphotos-a.akamaihd.net/hphotos-ak-ash3/559307_325955130827518_630404691_n.jpg