It's the square brackets.

my $res = $ua->request(POST $url,
[Content_Type =>'form-data',
Content => '',
Location => 'MM02',
Tickettype => '5120', 
CoreDirCorrect => 1,
PhoneNumber => '12335656787',
CustomerImpact => 3,
800014118 => 0,
Severity => 'HIGH',
InitialDescription => 'Test Request',
f=>'severalty',
tmpl=>'severalty',
SUBMIT1 => 'Submit Ticket Request']);
[download]

Update: On second thought, maybe it isn't the brackets afterall. This seems to work fine for me as well:

Content_Type =>'form-data',
Content => [
Location => 'MM02'
...
[download]

That'll teach me not to read the whole perldoc. For clarification...your error is happening in the Perl script, right?