He draws on his skills as a landscape painter to flourish the background of this scene with detail that fills every corner of the painting. Few artists of this time could do this quite so effectively and Carracci would make use of landscaped backgrounds where ever possible. In the case of this biblical passage, it made perfect sense to place the main figures within an overall setting such as this.
The way in which the figures are made particularly small in relation to the rest of the painting is intended to give the impression of a long and tiring journey, as dictated by the story in the Bible. It is however quite hard to make any emotional connection with the figures, though, because they are quite so small. Some artists from these traditional times would actually create series of related artworks, perhaps following the life of Christ over several passages of the Bible. These could then be presented together in the same room or building.
As mentioned elsewhere, Annibale Carracci is far from the only artist to have addressed this theme at some point in his career. There are many other memorable contributions from during the Renaissance to the Baroque era of which Carracci was a member. As styles changed and developed, so would the versions created of this Christian passage. Besides Annibale's own, other notable paintings included Rest on the Flight into Egypt by Caravaggio, Landscape with the Flight into Egypt by Pieter Bruegel and Rest of the Holy Family during the Flight into Egypt by Anthony van Dyck.