perldiag explains the error message further:

Multidimensional syntax %s not supported 
(W syntax) Multidimensional arrays aren't written like $foo[1,2,3]. 
They're written like $foo[1][2][3], as in C.
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Perl handles multidimensional arrays as an array of references to arrays. In Perl, $saveurl[$i,0] isn't a 2d array (and, causes errors to be reported). You want $saveurl[$i][0], which represents an array of refs to arrays.

It's a little tricky at first. See perllol for details, and perlreftut. Those documents should get you going in the right direction.