Reservation on the DB bus - we have a rail saver pass

Haven't done a pass so I cannot answer your question directly. However, the bus is operated by the railroad company. We made reservations through the dbahn rail site and I assume you would do the same. You should get prior reservations. Our bus was full when several walks ups tried to get on and could not. There is no bus station. Just a bus pick up point at the curb at the circle in front of the train station.

"...saver pass rail tickets on the DB bus." I'm not clear what you have there.

If what you have is a pre-purchased "saver" or "savings" fare TICKET for point-to-point travel between Munich and Prague, the IC Bus reservation is normally included in the price of the ticket.

If you have some kind of Eurail PASS or German Rail PASS that is valid for passage between Germany and Prague, then you do not have an automatic seat reservation and you need to reserve a bus seat. You can do that online at the DB website, as I understand it. Never done it myself.

And if you have a rail PASS - a flexi-pass that allows a certain number of travel days in a month, for example - then you might consider NOT using up a day of the rail pass for this trip. First of all, you have to pay extra for a reservation. Secondly, the Munich - Prague bus fare is cheap, often only €19. One day of a rail pass costs a good bit more than that, usually (divide cost of pass by number of days.) So you can save the rail pass day for use on some other day if you pre-purchase an online saver fare TICKET for this route.

If you really have "saver pass rail tickets", ie, Saver Fare tickets, from DB, they should have include seat reservations for the bus, plus the travel on a specific bus (date and time) is required. Is that what you have? Have you already received the tickets. Check them for seat reservations.

On the other hand, it what you have is a rail pass, either a Eurail pass or a German Rail pass, it doesn't look like you can make a reservation online (one of the many benefits of rail passes) since one end is outside Germany. You should probably call German Rail. The number is 049 1806 99 66 33. In my experience, there will be an announcement in German. If you don't speak German, just stay on the line. You will be answered by a real person. Ask if they speak English (they might. If they don't, they will understand you request and say "moment" and get you someone who does.)

You would probably be better off just getting Saver Fare tickets (with reservations) for the bus and save the rail pass day for another trip.

By phone

Booking period: from 3 months to 1 week before departure
Delivered to you within 5 business days by post

The Deutsche Bahn Booking Center operated by the German railways, can make reservations for most of Europe’s trains. Here’s how it works: You can call the Deutsche Bahn booking center on: +49 1806 996 633 (open 24/7). When you call, you’ll hear a German menu. Select extension ‘9’ for an English menu, then ‘1’ for train information and bookings.

The reservation service is free and you only pay for the reservation fee per person, per train. The cost to deliver your reservations is 3.50 euros to all countries. You can also pick up your reservations at a larger German train station. Just take your order number to a ticket window or a self-service machine at the station.

Lines can be busy during evenings (CET) and at weekends so you may have to wait a while to get through. Mention that you will travel with a Eurail pass, so that you only pay the reservation fee and not the full fare.

Please note that the DB Booking Center can't book any Thalys and TGV trains.

Other methods are also listed here