Magnum doesn't know the right word for a Windsor tie knot, but in an earlier episode he referred to a "double Windsor knot" on Rick's tie.
Higgins puts his fencing glove on just before Velma walks up to him, then in the close-up he is just starting to put it on.
In the UK no one displays the national country flag especially schools unlike America where flags are everywhere. Only official government buildings in UK display the national flag and then only optional rather than mandatory. A UK school whether State, Public or Private would not display the flag, this is a common mistake made by Americans.
Higgens while at school gets the cane. This was proper punishment at the time, however only one hand would be cained at a time, you would hold hand out palm upwards and at arm length. The other arm would be behind back. You would never be cained both hands at once. By doing one hand at a time is to give maximum pain.
TC is shown shirtless yet does not show any scars from being shot or stabbed. Two episodes earlier he suffered a near fatal gun shot wound to the chest but nothing is showing, and not a single wound suffered in Vietnam war is visible either on his body.
At minute 39, when Magnum talks about the case, there is the boom mic at the upper-left corner visible.