When they finished editing the movie for broadcast, the producers found out that they were actually a few minutes short so the elevator scene with Zack and Lyta was added.

Thirdspace was the first of the TNT movies filmed, but the second one aired, in July 1998. As it was actually filmed in late 1997, Claudia Christian was still part of the Babylon 5 cast at the time. When it was finally aired, Claudia had been replaced in the recurring cast by Tracy Scoggins in the part of Babylon 5 Commander under Sheridan.

The film takes place in April 2261.

The artifact was designed in cooperation with Wayne Douglas Barlow, author of Barlow's Guide to Extraterrestrials.

Leo Rosen was born in 2196.

Factual errors

Ivanova says (on Sheridan's link) that the carbon-14 dating puts the artifact at one million years old. But carbon dating can only be done to objects on earth, as the carbon ratios in space would be vastly different and constantly changing.

Even if the carbon ratios from the artifact's origin were known, Carbon-14 dating is only effective for dating things to about 60,000 years. Other radioisotopes would be used to date anything much older, yet Ivanova says that carbon dating determined the object is over a million years old.



Revealing mistakes

When Vir Cotto was throttling Zack Allen and the telepathic spell is broken you can see that Stephen Furst forgot to remove his wrist watch. The watch is not present on his left wrist when the fight begins, but is present at the end of the fight.

The countdown timer on the nuclear bomb starts at 4:00 minutes, but then begins counting down from 4:59, 4:58, etc.



Miscellaneous

When the IPX leader is looking at the various screens regarding the alien device, one of the displays has a misspelling: "EMF EMMISIONS" should be "EMF EMISSIONS."