You could try

my %replacehash = (
        TEMP1 => $flow->getExeName(),
        TEMP2 => $flow->getTempName(),
        TEMP3 => $flow->getData()->getNameType(),
)
[download]

(If you call a method with no arguments, like here, you could also omit the empty pair of parentheses, but that's not the point here.)

Also

my %replacehash;
@replacehash{map { "TEMP$_" } 1 .. 3} = (
        $flow->getExeName(),
        $flow->getTempName(),
        $flow->getData()->getNameType(),
)
[download]