Have you ever heard the tragedy of Darth Larry the Lightseated?

So I had to look. A 1200g (weight of the balloon) can lift about 12 pounds fully inflated. Most road kill you see are does, and they weigh probably about a 100lbs. We’ll figure you’d need some extra lift so if we went with 10 balloons that should be enough. Problem is I could only find 1000g balloons. Had to redo some calculations but I think it should be able to lift about 7.5 lbs give or take. So to get to the 120lbs of lift we’d need 16 balloons. The balloons are over $100 and you’d need 16 of them, so you’d need almost $2000 worth of balloons. And not to mention the helium which back of the napkin calculations we’d need about 1800 cu ft of helium. Given the data on price I found for spot delivery you’re talking likely another $2k for the gas. So for the low low price of $4000, you could really make somebody really confused when it lands in there yard.

Helium is portrayed as second most abundant element in the universe. Not scarce at all. Our ability to collect and make use of it, that's scarce.

A squirrel would probably need about 100 balloons.

Yep. We can place them on a diet, shave their fur, pump them full of helium... We have the technology.

That's why I'm listing the live weight. A dried-up rabbit carcass partially eaten by a fox will of course weigh less by a highly variable fraction, whose estimate I'm leaving up to you.

Probably not, the cluster of balloons would be so big you'd need a considerable amount of string, and at some point the overhead will be so big that each balloon will add more weight than lift.

Still, a moose is probably possible, just with more balloons.