When Annika is talking with Dr Strathearn about her boat after they come out of the museum she mentions "knots per hour" in reference to the boat's performance. A "knot" is a unit of velocity equal to one nautical mile per hour; to say "knots per hour" makes no sense.
Morgan is building a model of Thomas Telford's Menai Bridge, and tells Anika that this a truss bridge. It isn't. It's a suspension bridge, which has approaches each formed by a series of arch bridges.