This is a labelled toy model, not a real detector. One honest idea runs everything: a ripple of space stretches one direction while it squeezes the other, and only the steady pace of light can betray it - because light keeps its speed while a metal ruler stretches along with everything else.
What is real: the L shape, the 4 km arms, the 300 bounces and the 1,200 km light path, the 1/1,000-of-a-proton stretch, and the first event - September 14, 2015, two black holes of 29 and 36 suns, 1.3 billion years away, felt 7 milliseconds apart by the twin detectors. What is drawn: every stretch is enormously exaggerated (the screen says so), ripples move far slower than light, and the black holes are cartoons. The sources below are the audit trail for every number on screen. No journeys or personal details are used; nothing about you leaves this page.
Sources: LIGO Caltech ("What is an Interferometer?", "LIGO's Interferometer", "Gravitational Waves", and the 2016 detection announcement). The links are in the project readme.