This film is competently made and acted. No one can dispute that fact, but there is the problem. Its just competent. The excellent supporting cast is merely asked to do competent work, while capable of much more.
The leads, Conway and Ms. Long, while not really A-list actors, are also capable of more in the right role with the right production (for example Conway's work in Val Lewton films is excellent and perfect for him). But they are not asked to shine here and don't try to come up with chemistry between them. Instead, some sappy canned string music is used throughout all their romantic scenes together as a substitute for true romantic acting. I do believe it is the producer's or directors' fault, not the actors.
The courtroom activity rings true to me and I believe it is as a courtroom drama that this film succeeds. Succeed it does, but is relentlessly limited to "B" territory by the producers.
"A Night of Adventure", while rather standard and unimaginative, will hold your attention so you might want to view it if you are a fan of the actors involved. Fortunately none of the actors gives a performance that you could call less than "competent".