On the outward journey they meet no other ship to take Padde home. But Hajo's mother does receive a letter, sent while the ship is at the Cape of Good Hope.
The name Batavia for the Dutch settlement on Java was first used on 12 March 1619 and in 1621 became the official name for the town founded by Jan Pietersz. Coen. Willem Bontekoe left Holland in December 1618 as captain of the ship Nieu-Hoorn. According to the movie, they did not encounter any Dutch ships on their return voyage to Holland on which they could dispatch Padde back to his mother. The Nieu-Hoorn caught fire on 19 November 1619 (so: not shortly after New Year, as suggested) and therefore the boys could not have known the name Batavia when they were stranded on the little island off the coast of Sumatra.
Potatoes from the Americas reached Europe (Spain) in the middle of the 16th century. People were insecure of the plant because the berries are poisonous. It did not belong to the staple diet early in the 17th century (1618).
Pineapples, also from America, were imported in Europe as luxury products. They were not indigenous to South Africa, were the ship's crew are eating them, and were not spread outside the Americas and the Caribbean until the 18th century.
The flag of the Nieuw-Hoorn shows the word VOC with an L above the word. This L is the letter for the city of Lelystad, the home port of the retour ship Batavia, the ship used in the film. It should have been an H, as the home town of the retour ship the Nieu-Hoorn is Hoorn. Also, Lelystad is a "Brand new" city as it's build in the twentieth century from reclaimed seabed of the lake IJsselmeer (former Zuiderzee).
The ship Nieuw-Hoorn shows a steering wheel. Dutch ships in
this age used a tiller.