I always use the -x option when packaging to determine runtime dependancies. Let's take a short example:

marto@Shemp:~/code$ cat ff.pl 
#!/usr/bin/perl

use strict;
use warnings;

use WWW::Mechanize::Firefox;

my $mech = WWW::Mechanize::Firefox->new();
$mech->get('http://perlmonks.org');
[download]

Package 1:

marto@Shemp:~/code$ pp -vvv --log=pp_no_x.log -o ff_no_x ff.pl
[download]

Package 2:

marto@Shemp:~/code$ pp -vvv --log=pp_with_x.log -x -o ff_with_x ff.pl
[download]

diff the logs:

marto@Shemp:~/code$ diff pp_no_x.log pp_with_x.log 
2c2
< /usr/local/bin/pp: Writing PAR on /tmp/ppaOyYR.par
---
> /usr/local/bin/pp: Writing PAR on /tmp/ppLLOin.par
180a181
> /usr/local/bin/pp: ... adding /usr/lib/i386-linux-gnu/perl/5.22.1/St
+orable.pm as lib/Storable.pm
296a298
> /usr/local/bin/pp: ... adding /usr/lib/i386-linux-gnu/perl/5.22.1/at
+tributes.pm as lib/attributes.pm
394a397
> /usr/local/bin/pp: ... adding /usr/lib/i386-linux-gnu/perl/5.22/auto
+/Storable/Storable.so as lib/auto/Storable/Storable.so
396a400
> /usr/local/bin/pp: ... adding /usr/lib/i386-linux-gnu/perl/5.22/auto
+/attributes/attributes.so as lib/auto/attributes/attributes.so
603a608
> /usr/local/bin/pp: ... adding <string> as lib/Storable.pm
719a725
> /usr/local/bin/pp: ... adding <string> as lib/attributes.pm
817a824
> /usr/local/bin/pp: ... adding /usr/lib/i386-linux-gnu/perl/5.22/auto
+/Storable/Storable.so as lib/auto/Storable/Storable.so
819a827
> /usr/local/bin/pp: ... adding /usr/lib/i386-linux-gnu/perl/5.22/auto
+/attributes/attributes.so as lib/auto/attributes/attributes.so
851c859
< /usr/local/bin/pp: *** /tmp/ppaOyYR.par: 2141174 bytes read, 1823518
+ compressed, 14% saved.
---
> /usr/local/bin/pp: *** /tmp/ppLLOin.par: 2246924 bytes read, 1873647
+ compressed, 16% saved.
853c861
< /usr/local/bin/pp: Running /tmp/parl0GIttki -Lff_no_x.log -B -Off_no
+_x /tmp/ppaOyYR.par
---
> /usr/local/bin/pp: Running /tmp/parleAdFI2Q -Lff_with_x.log -B -Off_
+with_x /tmp/ppLLOin.par
856,859c864,865
< Packing "Config_git.pl"...
< Written as "Config_git.pl"
< Packing "Config.pm"...
< Written as "Config.pm"
---
> Packing "Config_heavy.pl"...
> Written as "Config_heavy.pl"
861a868,869
> Packing "Config_git.pl"...
> Written as "Config_git.pl"
864,865c872,873
< Packing "Config_heavy.pl"...
< Written as "Config_heavy.pl"
---
> Packing "Config.pm"...
> Written as "Config.pm"
[download]

The packages created are self extracting zip files, so you could just unzip and explore, but it's best to log and compare differences. This comes up fairly regularly, I'll work on a mini tutorial. See also Very Odd Issue When Using pp to Create an .exe File Including Date::Calc/Super Search.

-M Firefox/Application/API40.pm
-M Storable.pm
-M Sub/Name.pm
-M arybase.pm
-M attributes.pm
[download]