Some cases have not been captured in Salesforce using Web-to-Case but the user says they are still being redirected to the retURL. 

1: Is it normal for the form to not generate a case and still return the retURL?
2: Is there a way to see these cases that have not been captured? 

I have an external form setup on my website to collect support cases within Salesforce and is activated through a custom tab. Everything is working very nicely.
However, I would like the ability to have the Contact name and email auto-populated on the form when the link is clicked within Salesforce.

I am not sure if I need to build a VF page inside of Salesforce and iFrame it in my external page, or if there is a way to populate the desired information directly (through the link maybe?)

Any ideas would be greatly appreciated.