When Worf checks his personal log after the Cardassian attack on the Enterprise, he accesses "Any personal logs referencing the bat'leth tournament", the log mentions he will not be able to attend and his brother must take his place. But it still has the same stardate given in the other universes after the competition has ended.
In their quarters, Troi expressed concern that her Worf would not return when they closed the quantum fissure. When they made contact with the right Enterprise, they had a Worf on the bridge that dispels that hypothesis.
In one of the alternate timelines, Data states that Worf and Troi have been married for two years, one month, and twelve days. He also says that the romantic relationship -- not the marriage -- began shortly after Worf recovered from his spinal injury, but that would have been less than two years prior.
The goof item below may give away important plot points.
The changes Worf experiences always occur after he blacks out or becomes dizzy. But when Data activates Geordi's visor in sickbay, the change occurs before he becomes dizzy i.e. Worf's uniform and rank have already changed.
When Worf enters his room first time, there is a small round shield on the wall next to the doors with a red light pointing on it. After Deanna choose to hang Data's painting there, she put it away. Later, when the painting suddenly changes position, the shield doesn't return to its place. At the end when Worf returns to his universe and enters his room, the wall is still empty.