Today I noticed a strange bug in the Arena: I and other players had 5 team members at level 4, when only 4 slots had been unlocked. The Arena had selected an extra team member for me from my hand (not the one I would have selected) and was displaying that creature in the combat animation, even though it wasn't showing in the row labeled Your Team and couldn't be changed. Or at least, that's what I thought was happening.
When I refreshed the page, it turned out that I had already reached level 5. The bug was that the 5th slot simply hadn't been visually displaying as unlocked and the level meter (under the Round # header text) was incorrectly displaying as Level: 4 (3/4 XP).
