In the original script (and both sets of novelisations), Jinn is 'nodding [for Anakin] to go ahead'. I assume the hand gestures have much the same meaning.
JAR JAR and ANAKIN start to follow, then stop, noticing that OBI-WAN and
QUI-GON are staying with the SUPREME CHANCELLOR. QUEEN AMIDALA waves to the
duo to follow her. ANAKIN looks back to QUI-GON, and he nods to go ahead.
ANAKIN and JAR JAR join the QUEEN, PALPATINE, PADME, RABE and EIRTAE in the
taxi. PALPATINE gives the Gungan and the boy in the back of the taxi a
skeptical look. JAR JAR leans over to ANAKIN.
Then, to Obi-Wan’s surprise, the Queen waved at Anakin and Jar Jar to join her. He was about to stop them, when he saw Qui-Gon nod to Anakin. He arranged this with her before we landed, Obi-Wan realized.
The Phantom Menace: Junior Novelisation
Anakin started to follow, Jar Jar at his side, then stopped as he saw
that the Jedi were still standing with Supreme Chancellor Valorum.
Anakin glanced back questioningly at Qui-Gon, not certain where he was
supposed to go. The Queen and her retinue slowed in response, and
Amidala motioned for Anakin and the Gungan to join them. Anakin looked
again at Qui-Gon, who nodded wordlessly.
The Phantom Menace: Official Novelisation
It's not really clear why this was changed on the day, but probably the director felt that a nod was too subtle a gesture whereas pointing is pretty clear (e.g. "you go that way").