Traffic on the highway disappears when JR's car explodes.
The ages of the younger characters does not add up. While John Ross could conceivably be 17 (born 1979), Christopher should only be 15 (born 1981) and Pamela should only be 11 or 12 (born 1984/85). Yet they all look around the same age.
When Bobby Ewing rescues Julia Cunningham from the back of a galloping horse, the ground changes several times between grass in the long shots to sand in the close-ups.
John Ross and Sue Ellen are living in England. When Christopher phones him to tell him about J.R., the phone rings with a single American tone but British phones have a double ring.
There are over 2 years difference in age between John Ross (born 1979) and Christopher (born 1981). John Ross is 17 in this movie, as stated by J.R. That would make Christopher 15 - and yet Bobby lets him drive Pamela home without supervision. The minimum driving age in Texas is 16.
In his first scene, Cliff calls his secretary "Jackie" though her name is Debbie. (Jackie was actually the name of Cliff's secretary from the original series, though actress Sherril Lynn Rettino died in July 1995, a few months before this movie went into production).