Yes there are one outside Sevastopol, when we are into the comms just after taking the elevator we can see the same Alien inside the air ducts (from the same place where we saw the death of Hughes).
In the second mission, when you are discovering the station, there are three places where ypu can hear it and two more interesting : Just after taking the maintenance jack to Zach Watson, the trolley we saw just before is now reversed, the dishes on it roll on the floor and a stressful sound/music effect can be heard. And at the end of this mission, take the transit quickly otherwise it will appear behind.
In the third mission, the Alien can be seen in the Tech Support HQ after having left the big room with the rocket engine.
In the mission 7, when you are in Seegson Synthetics, in the synthetic fluid peocessing, the Alien can be seen taking a person while the others are shooting at it.
At mission 18, when you are activating the undoking of the Torrens, the Aliens which will attack you after can be seen at some places above and in front of you.
That's it !