Javier F. Mixpanel does not take any responsibility for leakages. This is what they say when you enable Public dashboards.
By enabling Public Boards you agree that Mixpanel shall have no liability for the disclosure of confidential sensitive or other information published via Public Boards.
For additional security, you have the option of creating a password that will be required prior to viewing your Public Board. Without password protection your Public Board will be visible to anyone who receives a URL, including the general public.
Public Boards can be disabled at any point in time.
You can still deactivate, or change passcodes at any point of time. But, unfortunately, there's no way to see how many users are accessing the dashboard.