The "replacement" Lancaster kit Emma delivers is in a much smaller box than the original.
As Steed briefs Mrs Peel about Psev in his flat, he refers to two large box files, each of which is marked 'PZEV'.
The Remote Control Hurricane firing at Steed shows footage likely taken from a war film of a 8 machine gun armed model while the RC model shown "flying" (on wires) is the model with four 20 mm cannon.
(at around 39 mins) As the model of the Lancaster bomber takes off, many wires can be seen as the model lifts into the air.
Both the model Hurricane held by Elena and the Lancaster have broken prop blades caused by damage from earlier takes when the models were thrown onto a hard surface.
The supposedly flying remote control aircraft all yaw (where the nose goes left and right) wildly which is impossible for an actual flying aircraft to do that quickly but is an unwanted consequence of the the wires holding the plane up being pulled.
When Col. Psev phones and asks them to watch the television and they move it over away from the wall it can clearly be seen that it has no power cord but they are still able to turn it on and watch it without a power source of any kind.
When Emma has a sneaky look around after delivering the model aircraft and waiting for the two pound payment, an extraneous moving shadow obviously of the film crew can be seen at the left side of shot.
It is never adequately explained whether or not John Steed was merely posing as his supposed "double" Gordon Webster all along and, if so, why didn't he let trusted agent, Emma Peel in on the subterfuge earlier in the plot (other than for the obvious contrivance of maintaining viewer suspense) even to the extent of denying his presence at the Embassy when Mrs. Peel sees "Webster" there while delivering the model airplane kit.
And if Webster was meant to be Steed's genuine double, then his ultimate fate was likewise left unresolved at the end of the episode.
CORRECTION: On two occasions Steec and Webster are in different places, most notably when the group watch Steed in a live TV transmission and when Steed is heard talking to Mrs Peel by the group, including Webster.
And if Webster was meant to be Steed's genuine double, then his ultimate fate was likewise left unresolved at the end of the episode.
CORRECTION: On two occasions Steec and Webster are in different places, most notably when the group watch Steed in a live TV transmission and when Steed is heard talking to Mrs Peel by the group, including Webster.