There seems to be an issue with the formatting of most Top Trumps sets, I would submit a correction request but since there are about 300 listed sets I figured a more general post was warranted.
Currently, most Top Trumps sets from the 2000's and onwards are listed as 31-card sets. That includes the thirty game cards and the title card that goes at the front.
The problem is that almost all of these sets have 33 cards. There's a title card, a backing card (usually with a barcode unless it's a promo), and a third card that's used for a few different things, like the Collect 5 promotion or advertising.
This 33-card format should be true for any set that has the hinged plastic shell design, which has been in place since 2000. I have the Simpsons set from that year for instance and it follows the structure. Some sets don't use the shell, and don't follow the structure, like promo sets or the "Britain at its Best" sets that still have three extra cards but they're for other purposes.
tl;dr Pretty much all Top Trumps sets with 31 cards in the checklist have 33 (30 game cards and 3 extra). The title cards should probably be moved to be a singular insert. Backing cards should also be added as a singular insert while the third one probably shouldn't until we know what it is for each set.