If those Martians are out there, they must be invisible. No movement at all.

8 seconds sound clip from the The Angry Red Planet movie soundboard.

You can hear this line at 00:28:47 in the Blu-ray version of the movie.

Quote context

[...]

- No surprises. The atmosphere is pretty much like we thought: thin, extremely thin.

- Not enough oxygen to sustain us, but undoubtedly enough for some kind of native animal life.

- Well, like you said, Professor, no surprises.

- You seen anything yet?

- Just those frozen vegetables.

- Any sounds?

- Not a peep.

- If those Martians are out there, they must be invisible. No movement at all.

- Weirdsville, as my grandmother used to say.

- Keep your eyes open, huh?

- Yes, sir.

- We've landed near the Equatorial belt.

- Now, if there is any native intelligence around here, it should be in this area.

[...]