Yes, you can customize your 404 page in LandingRabbit.
By default, visitors see your site navigation, footer, and a simple 404 message in the middle of the page.
If you want more control over that experience, you can create your own 404 layout as a regular page.
To override the default 404 layout, create a new page following these simple steps:
In LandingRabbit, create a new page by clicking the dropdown and choosing 'Blank'
Design the page content and layout however you like
Set the page path (also known as slug) to /404 and publish the page 
After you publish this page with the slug `404`, all 404 requests will use your custom page instead of the default layout.