Beginning with Tomica World in 1998, Thomas-series trains have often come with a small leaflet showing how to install the batteries for most if not all of the currently available range. As the ranges expanded, so too did the number of trains shown.
This initial Tomica World Thomas battery leaflet was used in 1998 when the individual release Thomas was the four-wheel type. At this point, there were only two styles of battery compartment.
The insides of these leaflets are not particularly interesting.
In 1999 the battery leaflet was updated to show the new six-wheel Thomas and how to remove its batteries.
From the marks on the back, it seems this is the American version of this leaflet.
As time went on and the range of characters grew, the amount of different batteries and battery compartments only grew... part of this is why you sometimes find characters with screws taken out or battery compartments left open.