I could see them run towards the shop; I could see them running towards the shop [duplicate]

None of them are incorrect.

English sense verbs, unlike most complement-taking verbs,
can take either gerund or infinitive complements.

• I saw/heard him leave/leaving.

This is most common with long-distance senses, of course;
-- She smelled him leaving is a fairly unlikely (though not ungrammatical) thing to say.

It may be (and undoubtedly some people interpret it this way, though others don't)
that

• I heard him leaving.

means something like (and may be a variant of)

• I heard him while he was (in the act of) leaving.

while

• I heard him leave.

means something like

• I heard the noise produced by his leaving.

Not a whole lot of difference here, and for all intensive purposes they're synonymous.