14 month old baby girl hit head really hard, knot formed quickly, no loss of conscientiousness and continued to play like normal after she stopped crying. Should I take her in? It's bed time, do I let her go to sleep?

I would take her to the hospital. My son hit his head on the coffee table at the same age. They did X-rays and an exam and kept him for observation for a while. It's better to be safe.

It's always better to be safe with a head injury, and have it checked.