I highly doubt that could happen at any moment, but the instructions told us to just get one cup per person and try not to spill a drop. Unless one of us decides to try to tempt fate and get hexed as the result.

(Harry wasn’t planning to stray away from what was instructed, although he was skeptical about the cups as his previous experience in retrieving Helga Hufflepuff’s Cup had enchantments placed onto the Gringotts vault Bellatrix snuck it into.)

The instructions didn’t mention about arrows at all besides possibly forewarning anyone about being too greedy.