The wings of all Trident variants are fundamentally the same, however the wings of the 3B are slightly larger than those of the previous models and have a greater angle of incidence.  They wings are swept back at an angle of 35° and have an aspect ratio of 6.43. Both leading edge slats and trailing edge flaps are employed as high lift devices except on the Trident 1 which features a leading edge droop.  The flaps are simpler in concept and operation than those on the American Boeing 727 aircraft which is similar in many other respects.  The 2E was the first series to employ the Küchemann style of wingtip, the 1E featuring a squared off tip and the 1C having a more conventional tip.  The wings had to be modified with a butt-strap and replacement of the tips with more conventional ones, after the discovery of wing cracks on series 3B aircraft in the late 1970s.

The Trident employed a highly unusual arrangement with the nose gear offset to the port side and retracting sideways to allow for extra space for avionic and blind landing equipment in the bay immediately ahead of the landing gear bay.  The nose gear has two wheel on a common axle.  The main gear pivot from a location in the wing, with two bogies and four wheels on a common axle on each bogie.  They rotate through 90° and then the wheels retract into a space in the wing fairing.

Trident 1Cs nose landing gear doors are both opening when the gear is down to allow access to the fuelling panel.

The pod housing the boost engine was used to house additional fuel and the APU in previous models and the "fin tank" was also deleted on the 3B.  The horizontal tail plane pivots roughly half way back along its chord and its incidence can be adjusted to trim the aircraft in pitch.

The three main Rolls Royce Spey engines are of twin spool low bypass ratio design, using axial compressors and turbines.  The combustion chambers are of the interlinked can-annular design and the engine features a complex shaped nozzle to integrate the hot and cold exhaust flows in an effort to reduce noise.  The aircraft was very loud compared to today's twin high-bypass ratio engined aircraft like the Airbus A320 or Boeing 737 NG.

Two engines are located in nacelles either side of the rear fuselage, while the third is located inside the rear fuselage, with an intake at the front of the vertical tail and an "s" duct leading to the first impeller stage.

The Rolls Royce RB162-86 boost engine, unique to the Trident 3B, is mounted in a pod in the tail above the central engine.  A small gas turbine engine is used as the APU (auxiliary power unit) to generate electricity on the ground and to start the other engines.  On most models, this is located behind the central air intake, with its own small air intake immediately above it and its exhaust is the square opening on the side of the tail behind the central intake.

The small engines and consequent low total thrust of the Trident proved to be its ultimate downfall.  With the introduction of Stage II noise compliance regulations, it would have been uneconomical to hush-kit the small number of remaining Tridents in the BA fleet and doing so may have limited their thrust output too significantly.  This meant the last passenger carrying operations back into the United Kingdom would have to take place by 31st December, 1985.