The sentence with the incorrectly placed modifying phrase is:
"Ana wants to buy new athletic shoes from her favorite store once she saves up enough money, Shoe Empire."
The modifying phrase "Shoe Empire" is unclear in its placement, as it seems to refer to the store but is awkwardly placed at the end of the sentence. A clearer construction might be: "Shoe Empire, her favorite store, is where Ana wants to buy new athletic shoes once she saves up enough money."