http://www.classic-british-motorcycles.com/triumph-thunderbird-unit-construction.html Skywatcher68's screenshot made at 01:17:10.
Just came across a photo which identifies the bike as belonging to Keenan Wynn.
It remembers me a "made for circus" sidecar I have seen in the Swiss national Circus many years ago Skywatcher68's screenshot made at 01:17:10. (01:21:18 01:21:20 01:23:05) Thanks to the last thumb: a 1960-1965 Harley-Davidson Topper, the only scooter made by Harley-Davidson. (Some other pictures and information in the US Scooter Museum website) ⇒ 1960 Harley-Davidson Topper (It's my first "first model on the IMCDb", I'm deeply moved )