This is related to issue #ZF2-457. Tested against zendframework-zf2-release-2.0.0rc4-2-g5dd58b8.

ZF2-457 was resolved by requiring the element to be of type Zend\Form\Element\Checkbox,

but Zend\Form\Form will return a Zend\Form\Element with get() if the element was added using add(array(...)).

However, if the element is first created and added using add($element), get() will return the correct type. Note that this applies to all other elements as well, eg. radio, text, etc. It seems safer to create the element and add it to the form rather than passing in an array of options.

// sample form which has 2 checkbox elements added in different ways
namespace Web\Form;
use Zend\Form\Form;
class Test extends Form
{
    public function __construct($name = null)
    {
        parent::__construct($name);

        $this->setAttribute('method', 'post');

        // adds element of type Zend\Form\Element
        $this->add(array(
            'name' => 'problemCheckbox',
            'attributes' => array(
                'type' => 'checkbox',
                'checked' => false,
            ),
            'options' => array(
                'label' => 'Problem option',
            ),
        ));

        // adds element of type Zend\Form\Element\Checkbox
        $element = new \Zend\Form\Element\Checkbox('goodCheckbox');
        $this->add($element);
    }
}

// sample controller action
public testAction()
{
    $form = new \Web\Form\Test();

    // returns object of Zend\Form\Element
    var_dump($form->get('problemCheckbox'));

    // returns object of type Zend\Form\Element\Checkbox
    var_dump($form->get('goodCheckbox'));

    return array('form' => $form);
}

// sample view script
<?php 
// causes fatal error as shown in Summary as get() returns Zend\Form\Element
echo $this->formCheckbox($form->get('problemCheckbox')); 

// no problems as get() returns Zend\Form\Element\Checkbox
echo $this->formCheckbox($form->get('goodCheckbox'));
?>