did Steven Spielberg really directed or did John Landis

I suggest you view 'Jaws' and 'Sugarland Express' and remember that John Landis only directed one film starring both Belushi and Ackroyd; the assertion 'who are usually in John Landis movies' is incorrect, and not much of an argument. While 'Blues Brothers' does contain a chase sequence and a general degree of chaos similar to the second half of '1941', it is because both use elements of Screwball Comedy to provide entertainment and a rapidly-evolving narrative. That said, one is more of a Buddy Movie, and the other has been frequently cited as not being funny enough to be an effective Comedy. You may be the judge on that score, since this film was far more successful with its audiences than with its critics. '1941' is vintage Spielberg- for those who understand this director's style. Several of Spielberg's signature elements occur here: like the protagonist of 'Jaws' and those of 'Sugarland Express' the film contains several 'Everymen'- ordinary, fallible people who find themselves in extraordinary circumstances, usually beyond their seeming ability to cope or find solutions to their problems; absolutely EXTRAORDINARY circumstances, like oh, maybe a war ('1941', 'Schindler's List', 'Saving Private Ryan', 'Lincoln'), an extraterrestrial invasion ('Close Encounters Of The Third Kind', 'ET: The Extraterrestrial', 'War Of The Worlds'), or an encounter with some kind of monster ('Duel', 'Jaws', and to a lesser extent 'Munich', since the protagonists set out to kill a monster, only to find other men exactly like themselves), creating either a fight to the death, an epic survival journey, or some kind of soul-changing odyssey within the minds of the protagonists themselves. In the case of '1941' I would say this particular theme is developed lightheartedly at best, but given Spielberg's primary inspirations (psychological effects of Pearl Harbour bombing, several 'war scares', and the Zoot Suit Riots of 1941) it is safe to say it is no less important.

I would guess that just from the unseriousness of the movie. Spielberg seems a bit too uptight for a movie like this.