Continuity mistake: Series 1, Episode 9: Primal. As Carter and Taggart are crawling through the access tunnel, the torch attached to the side of Taggart's goggles is pointing downwards, below his line of vision as established by the lenses on the front. As the shot changes to a close-up on Taggart, the torch is now pointing forwards, aligned with the lenses.
Plot hole: Tess sends Jack an airline ticket to visit her in Australia. The ticket reads 'From: Eureka, Oregon, To: Sydney Australia.' Seems odd that a commercial carrier would have a terminal in the most secret town in America. Eureka is a town created by the US government for its top scientists to experiment with new technologies. It is made nearly invisible from the outside by giant holograms. Very few non-residents even know of its existence.
Add timeGrumpy Scot
Factual error: Henry Deacon says people only use 10% of their brain at any one time. That's complete garbage - at times we may use quite a small part of our brains, other times the whole brain lights up with activity. The "10%" myth has absolutely no basis in fact - no-one even seems to know where this figure came from! Given the intelligence of Eureka's residents, Henry (and indeed others in the room) would know this.
Add timeJon Sandys
Continuity mistake: When Andy pushes Jack out of the way when the F.T.L. is malfunctioning he is pushed into 2 stacks of crates, they are seen all falling away from him. The next shot of him he is just falling against the crates and one of them falls on him instead of away from him and the other stack stays where it is.
Plot hole: When Dr. Hughes is racing to save Allison when he thinks he is Carter from the events that happened in "I'll be seeing you" Henry says he is racing for a cliff, and that the cabin was just a hologram. But in the episode the Cliff was the hologram disguising the cabin. Henry even commented in that episode that he did not remember a cliff being there.
Continuity mistake: At the beginning of the scene where Dr. Grant gives Jack the crank for the satellite dish, Henry turns his hat around so it is backwards, later on in the scene it is now facing forward, then is backward again, then at the end of the scene he is seen facing it forward.
Revealing mistake: When Carter and Jo almost crash into the reflective smart dust wall on the road, Carter puts his hand up and waves it, to see his mirror image doing the same. Carter's mirror's hand movements are out of sync, which reveals that the "mirrors" are the actors, and the "real people" are doubles.
Plot hole: Carter is apparently just learning about Feynman's Day, which Allison explains as "Eureka's version of April Fool's Day." It's highly improbable that Carter could have lived in Eureka for five years and still be oblivious of this, especially given all of the hijinks that happen.
Other mistake: When Holly and Fargo are playing Dungeons and Dragons, Holly rolls a d20 die and yells, "Critical hit!" but we can see the 20 on one of the upper sides of the die, meaning that she actually rolled a 2, which is most definitely not a critical hit (and actually nearly a critical miss).
Continuity mistake: Sheriff Carter has only one Jeep Cherokee for his staff. It constantly changes from a 1989 to a 1990 model throughout the series. This can be caught easily by looking at the triangular window near the hinge on the front doors. Jeep removed the tilting hinges on the window after the 1989 year was discontinued. This happens throughout season one and two.
Other mistake: Captain Eureka losing his finger makes absolutely no sense. He doesn't cry out in pain, there's no blood, and where the finger ended up is completely illogical. The finger didn't just sever on its own; it's shown that severing only occurs when passing through objects. Captain Eureka goes through a wall that is a good fifteen feet away from where the finger is discovered, and it is implausible to think it could have rolled there on its own.
Other mistake: When the parents freak out about Brian being missing, the back of the camper is shown, as is the part of the camper that's missing due to the distortion sphere. But it doesn't make sense; there are some parts of of the camper that shouldn't be there, mainly the one piece above the ground, where the sphere scorched the pavement but left the camper's end right above it completely intact.
Continuity mistake: At the end of the previous episode, when Carter tells Grant not to plan the wedding just yet, Carter leaves Cafe Diem and Grant says "May the best man win," as an aside. In this episode, the replay shows Grant saying this while Carter is still in the cafe, just in front of him.
Other mistake: When Allison video calls Jack as he's finishing bathing, apparently she can see below the belt, as she remarks for him to cover himself up. But he gets dressed and doesn't move any reasonable distance from the screen, and we then see Allison's view which only captures Jack's torso, so she never would have seen his privates anyway.