Yes, a clean get away from those evil... Mushrooms? Well, whatever the case I can tell it's serious because Dipper looks more distressed than usual, yet Mabel as always takes it in stride. Neat effect as they rise up from the dark forest up into the light above the clearing, perhaps adding some extra safety.
Actually, the other trees look a bit like they have feet, so I wonder if they were the problem. Doesn't matter because the escape is the fun part.
It's more fun for me to think there's a story behind it, and with it being dynamic and emotional I figured there had to be something serious happening. Even if we don't know exactly what it's still an action scene.