Sometimes when you open a chest, the animation can be interrupted. This can happen if you are in a queue and a match starts, or if the game crashes for example.
However, even if you are not shown the animation, you will still receive your items.
Please keep in mind that you could have received outfits, mounts, weapons, Tokens, titles, avatars or poses, so it will take you a bit of digging to find out what items you got. Also note that all duplicates will become Tokens, so your Token count may have gone up!
If you have thoroughly checked your account and are certain you did not receive any drops from a chest, please submit a ticket with the date and time (including timezone) and our customer support will determine what items you received.