1. Famous Bollywood choreographer P.L. Raj's full (real?) name is Peter Lewis. He adopted the name Raj to avoid the minority tag. Remember, even Yusuf Khan had to adopt a more audience-friendly name! Also, P.L. Raj is the father of Leslie Lewis (Lezz of Colonial Cousins).
2. In the film Jaane Bhi Do Yaaron, the names of the two main protagonists are Sudhir Mishra and Vinod Chopra - after the two filmmakers. They were classmates with Kundan Shah at the FTII and the trio had a pact that whoever got the first break would name characters in his film after the other two!
3. Product placements have almost become the norm nowadays. But when the trend was still in its infancy, there came a movie called English Babu Desi Mem (1996) - starring Shahrukh Khan and Sonali Bendre. It had the most audacious product placement by Bhilwara Suitings. They sponsored the hero's name. Yes, Shahrukh's name was Mayur in the film. (He was also endorsing the brand at that time.) Pity, not more than a hundred people saw the film!
4. In the film Khoon Bhari Maang, Rekha is shown to have gone abroad for cosmetic surgery after a murder attempt invloving a crocodile! When she lands back in India, she takes a cab at the airport and gives her home address. The address is "10th North South Road Juhu". Incidentally, the most famous house on that road is named Prateeksha! Coincidence?
5. Amitabh Bachchan's voice over for the introduction scene of Shatranj Ke Khiladi is quite well-known. However, his first ever cinematic assignment was also a voice over... in Mrinal Sen's Bhuvan Shome (1969). And he is duly credited as 'Amitabh'. This was probably before he left his job in Calcutta.
6. Karz is the one film which has the highest number of song mukhdas that have been made into films. It had four - Main Solah Baras Ki (Dev Anand, though not in the title role!), Paisa Yeh Paisa (Jackie Shroff and Meenakshi, I think), Ek Haseena Thi (Urmila Matondkar, Saif Ali Khan) and Dard-e-Dil (no details known).
Now the fifth has been announced - Om Shanti Om (Farah Khan's next starring SRK as Om and Deepika Padukone as Shanti)!
7. All the major stars of the day have acted in their debut films as child artistes. Aamir Khan as the child Tarique Hussain in Yaadon ki Baaraat. Hrithik Roshan as a super precocious kid in Bhagwaan Dada. Bobby Deol as the young Dharmendra in Dharam Veer. Karan Johar in a TV serial called Indradhanush (which had a very interesting plot about a time machine) - as a goofy friend of the hero. And if you are going to let me go even deeper, then I can include Shweta Bachchan whose mother was pregnant with her during the filming of Sholay.
8. A common misconception is that Nargis was the first Indian actress to appear in a swimsuit on screen. Actually, the first ever swimsuit scene in Hindi cinema was in a film called Brahmachari (not to be confused with the Shammi Kapoor one) - and it was done by an actress called Meenakshi. Boldness clearly runs in the blood as she has two grand-daughters - Shilpa and Namrata Shirodkar!
9. MBAs are extremely under-represented in the professions of Hindi film heroes. Probably the earliest was Jeetendra - in a film called Sharda - where he joins a company and then marries his boss' daughter! The great Mithunda was asked to get a diploma from Ahmedabad (by his wife - Moonmoon Sen) before he landed a high paying job in the film Sheesha. He molested his secretary immediately afterwards. Incidentally, his secretary was Mallika Sarabhai - a real-life graduate of IIM-A! Atul Agnihotri (Veergati) and Anil Kapoor (Hum Aap ke Dil mein Rehte Hain) are other self-confessed MBAs. The last one I can think of is Hrithik Roshan (in Kabhi Khushi Kabhie Ghum) cons his dad to finance a MBA in London - but sings songs with Kareena at a thong-prom instead!
10. RD Burman probably has the highest number of uncredited hits - as per industry folklore. A large number of 'fast tracks' credited to SD Burman is rumoured to have been composed by RD, because of the elder Burman's distaste for western music. Starting from Sar jo tera chakraaye (Pyaasa) right down to Roop Tera Mastana (Aradhana), many of them are attributed to RD.
Another apocryphal story is of the first break he got. His friend, Mehmood was about to produce a film and RD assured that he would convince SD to compose the music. Buoyed by RD's confidence, Mehmood had already drawn up the contract (on stamp paper) when he landed up at the Burman residence. Hearing the 'modern' story, SD chucked both of them out. Mehmood did not have the money - neither to get another stamp paper nor for any other music director. So, he just crossed out the Sachin in the contract and wrote out Rahul instead!
I hate using this cliche - but, the rest is history!