Security with PHP and HTML
===

I have designed php and html code around an API.

The html code allows users to type in a specific item for evaluation. The item is then posted to the php and run through the API. It gets the response and spits out a php page.

The API is well protected, but I"m wondering if there's anything that could go wrong within my pages, both PHP and html. 

Let me know if you can come up with anything that might be detrimental. 