I think there is an error in this rule:
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[Authority state]
If c is one of EOF code point, "/", "\", "?", and "#", decrease pointer by the number of code points in buffer, set buffer to the empty string, and state to host state.
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This is because if we take the following URL:

http://example.com/path

In the Authority state when we reach the last '/' character the buffer will contain "example.com", or 11 characters.  So we move back 11 characters so that the pointer now points to the first "e".  But after we move to the next state the parser now reads the "x", or the second character in the host.  This is obviously not correct.  So I suggest the following to correct this:

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[Authority state]
If c is one of EOF code point, "/", "\", "?", and "#", decrease pointer by __one plus__ the number of code points in buffer, set buffer to the empty string, and state to host state.
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