How do they travel so fast in Futurama?

Question

The speed in which they can travel in spaceships seems way higher than lightspeed, despite it being stated in one episode that their spaceship can only travel up to 99% of the speed of light.

For example, in one episode they manage to get to the frontier of the universe in approximately a week and in other episode they also reach the limit of the universe as they are sent to an invented planted that doesn't really exist inside the universe.

It's also obvious that the action is supposed to be happening in our universe in the future, the facts that confirm that it's huge.

I haven't watched all episodes, so maybe in one it's explained that's it's via wormholes or something like that.

Answer 1

Per "A Clone of My Own"

Farnsworth: These are the dark matter engines I invented. They allow my starship to travel between galaxies in mere hours.

Cubert: That's impossible. You can't go faster than the speed of light.

Farnsworth: Of course not. That's why scientists increased the speed of light in 2208.

This neatly explains why the ship is able to travel at 99% of the speed of light, yet still able to reach distant galaxies in mere hours.

Leela: For Heaven's Gate, Professor. This ship can do 99% light speed. Why are we going 35 miles an hour?

Farnsworth: Because we're in a hurry, that's why.

_{^{Teenage Mutant Leela's Hurdles - Transcript}}

Answer 2

By using the Dark Matter Engine

The Dark matter engine is the key to the extreme acceleration capabilities of the modern space ship.

Albert Einstein's famous statements that it would be mathematically impossible to travel faster than light seem to have held up throughout the 3rd millennia, and although in 2208 the scientific community allegedly raised the speed of light so that they could go faster, the problem that one cannot go faster than the speed of light remains.

The solution was the dark matter engine, which doesn't move the ship through the universe, but instead moves the universe around it at phenomenal speeds and is thereby able to cover incredible distances in a relatively short period of time.
^{_{—Futurama Wiki, Dark Matter Engine (link)}}

Answer 3

The ship has dark matter engines that allow it to move faster than light. Also, remember that scientists increased the speed of light in 2208.

In the episode 'A Clone of My Own' the Professor takes Hubert outside of the ship to explain how it travels faster than light. At the end of the episode we see a demonstration of it as the space around the ship is actually moved while the ship is stationary.

It's also a mix of the 'L-unit' and dark matter reactors.