The content inside the [code] BBcode tag has a direction defined as "ltr" (left to right) even with rtl languages.

In proSilver, you can find that trick in bidi.css (RTL definitions)

.rtl code {

	direction: ltr;

}

However, that definition is completely absent in print.css, and bidi.css is not loaded in "print view" mode (available in viewtopic and ucp_pm_viewmessage). That means that, if you use a RTL language (such as Arabic or Japanese), the content of code is displayed as a ltr content in normal mode (just like with western languages) but as a rtl content in print view