[oakwhiz]

The last word contains checksum bits but not all of the bits it represents are checksum bits. It just so happens to be possible for all of them to be the same word here. In this case it can be bacon (139th word) or one of the following: cupboard, double, jelly, neutral, review, smile, voice

[arcane_node]

Exactly what oakwhiz said. Similarly, if you set all 256 bits of the entropy portion to 1 (i.e. you play minesweeper with my grid) then the resulting valid mnemonic is zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo vote. The last word contains the checksum, which is the hash of the string of 1s.