documentclass[]{article}
usepackage{circuitikz}

usetikzlibrary{shapes.symbols}

begin{document}

begin{circuitikz}
draw node[shape=signal,draw=black, anchor=east]{Signal 1}
to [R=R1] ++(3,0) node[shape=signal,draw=black, anchor=west, ]{Signal 2};
;
end{circuitikz}


begin{circuitikz}
    draw node[shape=signal,draw=black, anchor=east]{Signal 1}
    to [R=R1] ++(3,0) node[shape=signal,draw=black, anchor=east, rotate=180]{rotatebox{180}{Signal 2}}; %This Works!!
    ;
end{circuitikz}

begin{circuitikz}
    draw node[shape=signal,draw=black, anchor=east]{Signal 1}
    to [R=R1] ++(3,0) node[shape=signal,draw=black, anchor=east,  rotate=180]{Signal 2}; %This Doesn't!!
    ;
end{circuitikz}

begin{circuitikz}
    draw node[shape=signal,draw=black, anchor=east]{Signal 1}
    to [R=R1] ++(3,0) node[shape=signal,draw=black, anchor=west, shape border rotate=180]{Signal 2}; %Nor Does This
    ;
end{circuitikz}

end{document}