The time jet is an example of a reliable computer system.

The time jet is introduced as the first technology of the movie. Ryan Reynolds' character, (Old) Adam, is evading authorities, attempting to steal the spaceship [1:05]. The capabilities of the time jet are: time travel, voice calls, and signal jamming.

Adam receives a transmission from Sorian, who is in the chasing ship [1:50]. She tells him to surrender but he crashes their tracking signal and escapes. The ship is badly damaged, and Adam uses the last of its abilities to perform time travel. Time travel is made possible by travel through a controlled worm hole.

Even when damaged, the time jet performs its functionalities. When Adam is getting chased, he uses the ship's signal jamming system to prevent Sorian from tracking him into the wormhole, then the ship performs time travel! After crash landing the ship in 2022, the ship begins to repair itself, restoring its functionalities [16:40].

A computer is reliable if it consistently performs its designed functions as intended. The fact that the ship performs its funtions under the circumstances of severe damage proves its reliability. The fact that it also repairs itself to restore functionality is beyond reliability.

The arc accelerator is an example of an unreliable computer system.

The accelerator was created by Adam's father, Louis, and it was designed to work with his specially designed algorithm to power time travel. The accelerator presumably worked in the previous timeline, as it progressed to the time jets of 2050, but the problem with the accelerator that becomes apparent in this new, altered timeline, is that it is delicate.

When Louis attempts to remove the hard drive which stores his algorithm from the accelerator, he says it will either continue to run on a loop, "Or there's a cataclysmic meltdown that will destroy all living things within 100 miles" [1:19:21]. Louis designed the hard drive to be removable but is not certain whether it will cause the machine to self-destruct. With such a powerful and dangerous machine, this is an unacceptable oversight.

The machine is also not very safe from outside threats. After one gunshot to the glass container, the accelerator's electro-magnet begins to meltdown [1:21:40]. A gunshot is such a small disturbance considering the magnitude of the particle accelerator. If something fell from the ceiling and hit the glass, it could have the same effect.

The meltdown was contained, however, by secure vacuum-seal doors. Necessary precautions were taken to contain any potential meltdown, and catastrophy was narrowly avoided.

The fact that the meltdown was contained after the matter does not prevent the machine from being completely destroyed by its lack of protection. It was ethical practice to make sure "all living things within 100 miles" are not threatened, but it was unethical that such an expensive machine could be made completely useless by cracked glass.

The second rule of the Software Engineering Code of Ethics and Professional Practice states that "Software engineers shall act in a manner that is in the best interests of their client and employer consistent with the public interest" [1]. Machines need to be built with safety and reliability in mind. The larger the machine and the larger the investment, the more care should be put into ensuring these things.