We discovered that the "Add query_vars" form field was saving/displaying the opposite of what it should. Here's a fix:
Before (starting at line 327 in mobile_client_detection.php)
<h3>Add query_vars 'platform' & 'browser':</h3>
<select id="add_vars" name="add_vars">
<option value="0"<?php echo(($mcd_options[3]==1)?' selected="selected"':'');?>>Yes</option>
<option value="1"<?php echo(($mcd_options[3]==0)?' selected="selected"':'');?>>No</option>
</select>
Fix (starting at line 327 in mobile_client_detection.php)
<h3>Add query_vars 'platform' & 'browser':</h3>
<select id="add_vars" name="add_vars">
<option value="0"<?php echo(($mcd_options[3]==0)?' selected="selected"':'');?>>No</option>
<option value="1"<?php echo(($mcd_options[3]==1)?' selected="selected"':'');?>>Yes</option>
</select>
http://wordpress.org/extend/plugins/mobile-client-detection-plugin/