Goofs

After the helicopter dogfight where Biggles says they are not armed after landing and asking for weapons he talks to Ferguson who has somehow found a Sterling submachine gun. The Sterling was developed during WWII and adopted in 1953.

When Jim Ferguson first visits Colonel Raymond at Tower Bridge, Raymond hands Ferguson an antiquated 'Celebrity Dinners' card. When Raymond passes Jim the card, it is in a plastic sleeve, then the camera shows the card in detail without the sleeve, and then it returns when Jim hands it back.

As Biggles and Raymond approach the sound weapon, the speaker is on the left side of the helicopter. As Biggles turns away, the speaker is now on the right side. But in the very next scene with the helicopter, the speaker is, again, on the left side of the helicopter.

When Biggles & Ferguson first meet after Biggles plane has crashed, Biggles face is clean. When he starts to run away he turns to speak to Ferguson - his face is now covered in oil.

After Jim & Debbie travel forward to London (with Jim firing on the police outside the Tower Hotel), they split up and Jim bumps into Biggles on the roof of a building. Biggles asks Jim where he's trying to get to, to which Jim replies Tower Bridge. However, Jim must have crossed the bridge to get to his location as the Tower Hotel and the tower of London can clearly be seen, on the other side of the river. (The HMS Belfast can also be seen close to the riverbank, which is also on the opposite side of the river to the hotel).

In the factory of the Germans, there is a sign with the following German text on it: "Achtung Hochstannung" ("Attention High voltage"). The word "Hochstannung" is misspelled! The correct word is "Hochspannung".

Colonel Raymond's quarters have a blazing fire, despite the fact that there are no chimneys in Tower Bridge.

During the helicopter dogfight, you can see Millbrook proving grounds which wasn't built until the 1960s.

When Ferguson enters Tower bridge for the first time, he takes an impossible route to Raymond's home. Firstly he enters the door to the South Abutment tower, then passes the old steam engines which were removed in 1976 and moved to the south bank as museum exhibits, then ends up in the South Main Tower. None of these areas are connected in any way other than they separately make up components of the bridge as a whole.

After the Sten gun is dropped and the police are running past instead of spent casing there are "complete" shells laying on the floor.

When Biggles is talking with Peter Cushing's character in Tower Bridge, there is a raven stood upon a perch. Immediately after Biggles comments on the photograph of him and his colleagues, the bird is seen to defecate. The microphone even catches the sound of the dropping hitting the floor.

The weapons are Bergmann type smg's which are correct for the era.

The World Trade Center complex, seen in several establishing shots of New York City are incorrect for the date the movie is set. The first shot doesn't include the towers at all, and the other two shots show them being constructed and without a spire for the North Tower, dating the footage to 1973 and before, 13 years before the movie is set.

At many points during the film the heroes use machine guns, it looks as though every one is a Sten gun type, which weren't in use until the late 1930's.

Some scenes supposedly in New York are obviously filmed in the UK, evidenced by the visible UK road markings.

William Raymond (Peter Cushing) said that he was Biggles' Superior Officer during WWI. But according to Cushing's interview on the making of, he said that in the script his character was 80 years-old (he was 71 during filming). If his character was 80 years old in 1986, that means he was born in 1905/6, and then he was 12 in 1917. His character then should be much older in the 1980s.