This happened to my DD around 5 years ago, she was 2 and in nursery, like you her dad picked her up and was too shocked to ask questions as he just had a form thrust in his face to sign and was ushered out quickly.
She had fallen down a set of stairs, had burst open her mouth, scraped her nose and had a bruise on the side of her head running down to her eye.
It had happened around 2 hours before we were collecting her, she had cried for that 2 hours.
We pulled her out that day, i sent them a huge email, never paid my fees for that month, or my one months notice or my cancellation fee.
They never even questioned it, i think they were just happy to get rid of me and hoped that would be the end of it.
To be honest there was a few red flags like every time we came to collect she was crying, she had her jacket on in the room as if she was all ready for us but we collected at different times between 4 or 5pm so i wondered how long she had been sitting in her jacket for, she also came back filthy, and im talking like her face her arms everything with either white paint or mud, its as if they never washed her.
The nursery was shutdown about 6 months later then taken over by a larger well known chain