Thanks for asking! One of my passions is space exploration, and I made sure to name my company after something that would let me talk about the space program any time someone asked me.
While I wish it were a portal through space and time, Door 44 is actually one of many access panels on the side of the space shuttle orbiter allowing engineers to reach the avionics and other critical components. This door is particularly special, because when you crawl into it (from just above the orbiters starboard wing), it has an exit: directly into the cargo bay of the shuttle.
It was my great privilege to crawl through this door on the space shuttle Atlantis while she was being decommissioned at the end of the shuttle program.