Render an array in Block_view
I don't think $block['content'] = '&lt;a href="/19"&gt;'; $block['content'] .= '&lt;img class="pimg" src="'.$row-&gt;uri.'" alt="Se alle vores filter elementer her"&gt;';... will work, . is a string(concatination) operator. You should create render array and assign it to $block['content'], example: 

$array = array('#markup' =&gt; 'SOME HTML');
$block['content'] = render($array);


EDIT:

After below comments, I played a little with hook_block_view hook, and I found out some information about it:


$block[subject] doesn't affect to its content even if you don't set it; content will be displayed without any subject (so, your missing subject doesn't cause any error here, as j.Reynolds mentioned);
$block['content'] can be string value and you don't need to render it, as Molot andj.Reynolds mentioned below, and you can concatinate it as many times as you want:)


So, if we return back to your snippet, you can try something like this:

$block['content'] = '&lt;a href="' . url(19) . '"&gt;&lt;img class="pimg" src="'. image_style_url('STYLE_NAME:E.G:LARGE', $row-&gt;uri) . '" alt="Se alle vores filter elementer her" /&gt;&lt;/a&gt;'; // assuming that anchor tag will wrap img          
$block['content'] .= '&lt;p class="pname"&gt;' . $row-&gt;title . '&lt;/p&gt;';
$block['content'] .= '&lt;p&gt;' . $row-&gt;body_value . '&lt;/p&gt;';      
$block['content'] .= theme ('item_list',array('items' =&gt; $items, 'type' =&gt; 'ol',   'attribute' =&gt; 'produkt'));


I don't know what $row-&gt;uri looks like in your code, but I assumed that it is something like public://FILE_NAME.EXT, if so you can use image_style_url function to generate image src..