The dropdown on the right is in a table cell, this works as intended on desktop browser.
However on mobile, on click, the dropdown gets split into two lines:
HTML
<table class="table table-striped table-bordered table-hover">
<tr>
<td> ... </td>
<td> ... </td>
<td> ... </td>
<td>
<div class="btn-group">
<a href="#" class="btn btn-primary btn-small"><i class="icon-eye-open icon-white"></i> Visualizza</a>
<button class="btn dropdown-toggle btn-primary btn-small" data-toggle="dropdown"><span class="caret"></span></button>
<ul class="dropdown-menu">
<li><a href="#"><i class="icon-pencil"></i> Modifica</a></li>
<li><a class="btn-confirm" href="#"><i class="icon-trash"></i> Elimina</a></li>
</ul>
</div>
</td>
</tr>
</table>
The problem most likely stems from the table cell width being laid out too short for both elements.
The simplest solution would be to set add a class to that cell and add min-width, though you would be moving away from pure bootstrap.
HTML:
<td> ... </td>
<td class="dropdownCell">
<div class="btn-group">
...
Css:
.dropdownCell { min-width:130px; }
Fiddle is here: http://jsfiddle.net/a4kx75t1/1/