The game can occasionally lag during the selection screen when you purchase a special crate. When this happens, the game will AUTOMATICALLY select a random item for you and place it in your Gift Box to make sure you're not missing out.
You're not losing any items, don't worry! If the game lags out, simply refresh the game and go to your Gift Box, and the items you won from your crate will be there! If you have a packed gift box, search through for an item you don't recognize. We can assure you we're giving out the items properly and have you covered.
Crates also show you items you COULD have gotten - once you've clicked on the crate to open it, sometimes it will show an entire selection of items that are ALSO available in the crate, but which you did not win. In this case, look for only the highlighted item!