I've really always loved that the physics surrounding the Alien seemingly make little to no sense or just flat out break. The entirety of Brett's death with the Alien's placement and how it drops and takes him back up into the vent, the Alien grabbing Dietrich and almost "levitating" up to nowhere, the red lit vent scenes where the Aliens barely touch the walls as they move, spinning and twisting around wildly, and the Runner crawling the smooth walls and ceiling in the chase sequence of
AlienĀ³.
Lastly, the closeup shot of the Egg as Kane inspects it shows the dark liquid on its surface literally running and dripping upward.
*Queue the heebie jeebies*