My goal here was to set up how they planned to get back to Charlotte's place without anyone seeing Annie. I suspected Annie had a backup plan if she had to look like a normal civilian on the street. She'd also have a way to carry something if she found evidence from the super-villain (although I'd wonder if she could carry a bag that big if it was full).
I thought about giving the two sexy outfits underneath, but it seemed like it would be too likely for them to believe they'd have to remove them and walk home.