Hi Daryl,
no, you are not missing anything. There is currently no time input in Forms.
Please check out uservoice and upvote the related posts.
My workaround is currently to use two decimal fields, one with min value 0, max value 23, the other with min 0, max 60.
I then build a normal time object using the workflow arithmetic expressions.
Hope this helps.
Greetings from Germany,
Simon H. Hellmann
DocuWare System Consultant