Balloons at the party
Balloons scattered on the floor is not recommended, this create a health and safety risk (trip hazard and choking hazard when bust) balloons on the floor may encourage screaming, running around and bursting of the balloons which can be disturbing to shy or younger guests and detracts from your entertainment
Plain helium balloons to give out at the end is a great idea - not only do kids love them, they serve as decoration during the party.
I am fine with them being in the hall permitting they are either tied up or out of reach of the kids.
If this is the case some management from your side might be required… If you have any littler ones at the party (3 and under), mums and dads tends to give them the balloons to play with as they are not able to fully engage with the entertainment. This can sometimes lead to a bit of interruption as other guest might also want a balloon then.
Balloons may encourage screaming, running around and bursting of the balloons which can be disturbing to shy or younger guests and detracts from your entertainment.
If this was to happen I would need for you to manage that as my focus will be on the children and making sure that your child has the best party ever.