Joe Root led the way for England with a sparkling century and with Moeen Ali, unbeaten on 99, helped them finish the opening day on 311 for four after opting to bat first.
England captain Alastair Cook led a charmed life against new-ball pace duo Mohammed Shami and Umesh Yadav when the left-hander was dropped twice in the first two overs behind the wicket.
Cook's opening partner Haseeb Hameed, making his debut aged 19, was also dropped on 13 and the pair added 47 for the opening wicket to give England a solid foundation to build on.
"In the first session of day one of a test match there's something in the wicket," former India all-rounder Bangar told reporters. "Whether you bat or bowl first, you need to make the first session count.
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"There were unfortunately a couple of dropped catches which did not allow us to make those early dents into their batting lineup... that set us back."
England had struggled with their opening stands last month in Bangladesh, where they drew a two-test series 1-1.
They had starts of 18, 26 and 10 in three innings before openers Cook and Ben Duckett compiled a 100-run partnership in the second innings in Dhaka.
"We could have definitely started well in that first session," said Bangar. "Had we taken those catches we would probably have been asking questions of their middle order.
"But full credit to them, they fully utilised the conditions on offer in Rajkot on day one.
"Rajkot is known to be a batsman's paradise and they fully utilised the conditions."
Bangar was hopeful the hosts, ranked number one in the world in tests, will bounce back on the second day.
"The game changes quickly," Bangar added.
"They are four down at the moment. A couple of quick wickets (and) we could make early inroads and wrap them up before a session and half. You never know."
(Editing by Ken Ferris)
