I don't get an error if I do that either, but (I think) that's because nothing has been initialised yet. Try this:

#! perl -slw
use strict;
use OpenGL qw[ :all ];

print "Version: ", $OpenGL::VERSION;

glutInit();
glutInitDisplayMode( GLUT_RGBA | GLUT_DOUBLE | GLUT_DEPTH | GLUT_ALPHA
+ );
glutInitWindowSize( 1024, 768 );

my $main = glutCreateWindow( 'OGL1' );

glutDisplayFunc( \&render );
glutMainLoop();

sub render {
    glClearColor( 1, 1, 1, 1 );
    glClear(GL_COLOR_BUFFER_BIT);
    drawPolygon(
        #### One too many arguments!!! (I'd added an alpha value)
        [ 1.0, 0.0, 0.0, 0.0 ], # red 
        [ 0.25, 0.25, 0.25 ],
        [ 0.75, 0.25, 0.25 ],
        [ 0.75, 0.75, 0.25 ],
        [ 0.25, 0.75, 0.25 ],
    );
    glutSwapBuffers();
}

sub drawPolygon {
    glBegin(GL_POLYGON);
##    glColor3f( @{ shift() }[ 0, 1, 2 ] ); ## Works
    glColor3f( @{ shift() } ); ## Fails
    glVertex3f( @$_ ) for @_;
    glEnd();
}
[download]

Switch the comment card in drawPloygon to see it work.

sub drawPolygon {
    glBegin(GL_POLYGON);
##    glColor3f( @{ shift() }[ 0, 1, 2 ] ); ## Works
    glColor3f( @{ shift() } ); ## Fails
    glVertex3f( @$_ ) for @_;
    glEnd();
}
[download]

In the call that works glColor3f() receives 3 arguments. In the call that fails glColor3f() receives 4 arguments - which rightly warrants a "Usage" error. The following rendition of sub drawPolygon works fine for me:

sub drawPolygon {
    glBegin(GL_POLYGON);
    my $arg = shift;
    pop(@$arg);
##    glColor3f( @{ shift() }[ 0, 1, 2 ] ); ## Works
    glColor3f( @{ $arg } ); 
    glVertex3f( @$_ ) for @_;
    glEnd();
}
[download]

Update: Duh, you'd already worked it out for yourself. I missed the "Solved" and didn't pay attention to the comments.

Cheers,
Rob