Surah 34:9
"Do they not look to what is before them and what is behind them of the sky and the earth? If We (so) please, We could cause the earth to swallow them, or make fragments of the sky fall on them. Surely in that is a sign indeed for every servant who turns (in repentance)."
Sky can Fall Down on People
The Qur'an author thought that the sky is like a ceiling that can fall on someone while the earth can swallow someone too. This is obviously impossible as the earth's atmosphere is simply made of gas.