We'll create fresh WordPress site with Limit parameter for gallery shortcode installed. You have 20 minutes to test the plugin after that site we'll be deleted.
By default, the gallery shortcode does not allow to limit the number of images displayed. This makes sense when you for example include all images attached to a post like this:
[gallery id="4"]
When this plugin is activated, you may use:
[gallery id="4" limit="3"]
and it will only display three images.
You can also use an offset parameter:
[gallery id="4" limit="3" offset="1"]
Will display at most three images, starting at the second.
Note that this plugin is a little bit of a hack.