This movie is more of a commercial movie than a thriller movie. The director could've avoided many songs in this movie. The concept of the movie was very new to the cinema at that time. We could enjoy this movie very much even if it gets released today.
When three different people tried to kill you on three different places and three different days of the same week, you wouldn't be singing songs and dancing in the rain along with kids. This movie has a lots of silly elements like this throughout till the end. But the story and screenplay kept the movie going.
I feel the director has inserted comedy clips into the scenes every once in a while to prevent the audience from boredom. But this made the movie to lag and the movie would've entertained a lot more without those silly jokes.