localtime[0..2] means localtime([0..2])

You are constructing an array with three elements, getting a reference to it and passing it to localtime. localtime treats the reference as a number, resulting in the address, and uses the address as the number of seconds since epoch.

use POSIX qw( strftime );
my $ref = [ 0 .. 2 ];
print($ref, "\n");
printf("%X\n", 0+$ref);
print(strftime('%Y-%m-%d %H:%M:%S', localtime($ref)), "\n");
print(strftime('%Y-%m-%d %H:%M:%S', localtime(0+$ref)), "\n");
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ARRAY(0x225248)
225248
1970-01-26 19:48:08
1970-01-26 19:48:08
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The parentheses are necessary to remove the ambiguity (by requiring an operator instead of an expression).

perl -MO=Deparse and perl -MO=Deparse,-p help with parsing problems.

Update: Corrected spelling mistake pointed by jwkrahn.