Try right-clicking on the .gif and select "show controls", if it's there. This works for me most of the time. It doesn't work at all for real .gif files, but it's true that most ".gif" files are actually auto-play looping videos with no sound and hidden controls.

Imgur and Gfycat convert gifs to either WebM or MP4—making them videos.

Imgur also introduced gifv—a faux extension—to easily identify video-enhanced gifs.

Of course, the internet is still full of glorious 256-color, chunky-sized traditional gifs.