Actually, contra my earlier post,

use strict
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would have diagnosed the problem after all.

#from http://www.perlmonks.org/?node_id=431329
#use strict; #Uncomment me to get to the root of the problem.
use warnings;

my %Hash = (
                ArrayInHash => [1,2,3,4],
                );

print "Array in hash: $Hash{ArrayInHash}";

#Only get error if you use strict;
print "WRONG Dereffed Array in hash: @$Hash{ArrayInHash}";
print "RIGHT Dereffed Array in hash with brackets: @{$Hash{ArrayInHash
+}}";
[download]

Use the strictures!