a chicken is not a mouse. Their bones are thicker, larger and less pliable.
Question:
Once a container is opened, wouldn't oxygen diminish the power of the mouse dissolving acid?
Not oxygen, but the loss of carbon dioxide as a gas removes the "carbonic acid" from the soda. I don't know if Mountain Dew (yuck!) is one of those products that adds phosphoric acid to the mix.
The primary acid in soda is phosphoric (Coke & Pepsi) or Citric (Mountain Dew, Sprite, etc). They are not strong acids but they do a pretty good job marinating meat and will leach calcium out of teeth and bones. Combined with Carbonic Acid in soda can for the time it takes to get from the factory to point of sale, it sounds plausible that a mouse would be reduced to an unrecognizable glob.
The point is that the weak acids in any carbonated product are not enough to dissolve a mouse or a roach for that matter. The oxygen content would work with an acid to speed up the dissolution of the organic material. Over a long period, longer than you would keep a bottle of Pepsi, the carbonic and any citric acid would break down some of the components but would not dissolve them. We did an experiment back in the 60s in 9th grade science that did something like this. That was when the first questions came up about soft drinks “cooking” your stomach. Crap science then, crap science now.