Revealing: When Hillard throws the basketball at Ripley, you can clearly see the white tape on Ripley's hand which was used to catch the ball.

Continuity: Ripley kills the alien in the corridor after it has killed the first member of the Betty crew but there is no melting of decks or bulkheads from the creature's acidic blood. Also, the Betty crew seem unaffected by all the acid.

Continuity: When the whole crew of the Betty are being arrested in the Mess Hall, Christie puts his hands behind his back to get the guns on his arms. But in the next shot when Christie is behind Wren his hands are by his sides. There's no way he could put his hands by his sides without the guns showing.