The basis of the book is a bet that the central character, Phileas Fogg, can in fact go around the world in 80 days, "now that the section between Rothal and Allahabad, on the Great Indian Peninsula Railway, has been opened"/"depuis que la section entre Rothal et Allahabad a été ouverte sur le « Great-Indian peninsular railway »" (Chapter 3 - NB that the French original spells the name of the railway correctly, unlike the English translation). It turns out that this information (and therefore the basis for the bet, but that's a different matter) is not true: the railway ends fifteen miles after Rothal at the hamlet of Kholby, as Fogg and his companions discover in Chapter 11, and the party continues on to Allahabad by elephant.
Rothal and Kholby appear to be unknown to today's geographers. We do have some clues: "The general route of the Great Indian Peninsula Railway is as follows: Leaving Bombay, it passes through Salcette, crossing to the continent opposite Tannah, goes over the chain of the Western Ghauts, runs thence north-east as far as Burhampoor, skirts the nearly independent territory of Bundelcund, ascends to Allahabad, turns thence eastwardly, meeting the Ganges at Benares, then departs from the river a little, and, descending south-eastward by Burdivan and the French town of Chandernagor, has its terminus at Calcutta."/"Voici, en somme, le tracé à grands points du « Great Indian peninsular railway ». En quittant l'île de Bombay, il traverse Salcette, saute sur le continent en face de Tannah, franchit la chaîne des Ghâtes-Occidentales, court au nord-est jusqu'à Burhampour, sillonne le territoire à peu près indépendant du Bundelkund, s'élève jusqu'à Allahabad, s'infléchit vers l'est, rencontre le Gange à Bénarès, s'en écarte légèrement, et, redescendant au sud-est par Burdivan et la ville française de Chandernagor, il fait tête de ligne à Calcutta."
This itinerary isn't difficult to trace today, apart from the bit traversed by elephant where the railway runs out because it does not cross the Vindhia Mountains. For the next two chapters the place names don't appear to correspond to anything I can find: we have "the village of Kallenger, on the Cani, one of the branches of the Ganges.... Allahabad was now only twelve miles to the north-east."/"la bourgade de Kallenger, située sur le Cani, un des sous-affluents du Gange... La station d'Allahabad n'était pas à douze milles dans le nord-est." But I can't even find the Cani, let alone the village of Kallenger (there is a Ken River, but it is just a bit too far to the west). Fogg rescues Aouda, the young widow of one of the rajahs of Bundelcund, from death by suttee, at the "pagoda of Pillaji", which again seems to be fictional.
Of course, Verne is writing a work of fiction, and on top of that the main purpose of this passage is to set up India as a contrast with America later in the book rather than to be a geography textbook. I can't shed any further light on Kallenger or the pagoda of Pillaji (though I do find Pillaji as a Marathan leader, but again this is too far to the west). However I think I have identified Verne's source for Kholby: I reckon it is his misreading of the town of Kothi, which is 80 miles as the crow flies (rather than 50 miles as in the text) from Allahabad, and twelve miles (rather than fifteen) north of the railway station at Satna (which therefore may be the basis of Rothal, though how you get from the one to the other orthographically I don't know). It's far from perfect; Kothi isn't actually on the railway line, which passes some way to the east of it. But I imagine that Verne was not striving for total accuracy. (Bill Butcher has more on this.)
Map of the area from 1893: