Goofs

When Kirishima is fighting the Saradian agent, the agent is able to grab his rifle. While he is taking aim, a rear view image reveals a large brown spot on the back of the agent's shirt that was not there before.

According to ransom demand fax, the deadline to turn over the anti-nuclear energy bacteria is no later than "2 pm Tuesday the 31st". However, when Kurshima arrives at the delivery location he checks the time and the date dial on his wristwatch reads, "Friday the 10th"

The Godzilla suit used in the water scenes visibly differs from the one used on land. It has a higher forehead with a ridge running across it, and its "cheeks" are also different.

In order for the bacteria to take effect on Godzilla, he has to be warmed up because he is cold-blooded. However being cold-blooded doesn't actually mean that an animal is cold. Just by his sheer size and mass, Godzilla's body would be radiating an immense amount of heat.

After Shiragami is briefly interviewed by the media, Biollante is shown for a brief second appearing regular, but in the very next shot with Biollante, it's fully blossomed.

In both the Japanese and English-dubbed versions, the same mistake about two agents being killed instead of one is left intact.

When the body of one of Biomajor's agents is being removed after the gunfight in Shiragami's lab, a man states, "The bodies belonged to two of Biomajor's agents", making it appear that two men were killed instead of one. In fact, the second agent is later seen making the negotiations to hand over the Anti Nuclear Energy Bacteria.