When Harry and Mr. Weasly get to the ticket gate in the underground Harry reaches for the ticket/card in his front pocket multiple times in just a few seconds.

First seen from behind just as they reach the ticket gate he lifts his arm to his front pocket pocket.

Second you see them from the front and just as Mr. Weasly bumps into the closed gate Harry again lifts his arm to his pocket.+

Third seen from back/side view as Mr. Weasly turns to Harry - Harry lifts his arm to his front pocket a third time.