Lots of little flaws in the writing, like when Seven is trying to tell if LaForge is a changling she could have just tapped her comm link to page the real one.
Discussion
Of all the people on a starship who would be analyzing energy surge patterns why of all people was it Dr. Crusher who figured it out?
The whole "the pattern resembles the contractions of mammalian labour" thing was really lame and I'm glad they didn't dwell on it.
There is also a terrible abundance of bad guys who can't aim for shit and good guys who never miss. What is this, star wars?
And why is it so dark on the bridge? There is literally no ambient lighting--it's all just control panels. Everybody knows that dark bridges are for the bad guys duh.