RefTeX TOC scans words in verbatim environments, too. And this makes TOC incorrect. For example,
\documentclass{article}
\begin{document}
\section{First}
\label{sec:first}
\section{Second}
\label{sec:second}
\begin{verbatim}
\section{Third}
\end{verbatim}
\section{Last}
\label{sec:last}
\end{document}
Section "Third" is in a verbatim environment and should not be shown in RefTeX TOC. But the RefTeX TOC buffer is shown as:
TABLE-OF-CONTENTS on ~/Documents/test/emacs/reftextest.tex
SPC=view TAB=goto RET=goto+hide [q]uit [r]escan [l]abels [f]ollow [x]r [?]Help
------------------------------------------------------------------------------
1 First
2 Second
3 Third
4 Last
Verified using Emacs 24.4 with AucTeX 11.87 on Debian 8.