Is there a reason to use a hash instead of an array for the first layer (update: or even the dynamic data)?

@data = (
          {
                  # Not quite certain what purpose this serves
                  # 1 => "", #dynamically created
                  # Perhaps something like this instead...
                  dynamic_data => [ ... ],
                  name => "",
                  that => "",
          },
          # ... and so on
);
[download]

Then, your code would instead be ...

push @{ $data[0]{dynamic_data} }, "blah";
push @{ $data[0]{dynamic_data} }, "bleh";
[download]

I would rename dynamic_data to something more descriptive, of course.

Perhaps a description or example of how you use the data or what it represents might help shake out an appropriate data structure.