I believe it was Revision 1.4 that featured the faulty expansion sequence.
For Reptile/Sub-Zero/Scorpion, the first sprite prior to inflating, and the last one before exploding (shown above) were corrupted and only partially visible. The two sprites were removed in the following update, leaving the ninja's with only four total in the fatality sequence.
Despite the arcade trouble, the PC-DOS port of MKII features the entire sequence proper. I'm pretty sure it's the only version out there that actually does.
I appreciate the compliment, but I cannot take credit for ripping the two defective sprites. I downloaded a complete sprite pack for the MKII ninja's and it just so happens they were included in the folder.