This is the first time Sheldon is seen driving with an actual driver's license. He obtained a learner's permit in The Euclid Alternative (2008) and drove Penny to the hospital for an emergency in The Adhesive Duck Deficiency (2009), but always claimed that he never got a real driver's license. That is, until The Space Probe Disintegration (2015) where he admitted to Leonard that he had obtained a permit after Amy gave him lessons, but kept this quiet (even from Amy) since he prefers to be driven around. In The Allowance Evaporation (2017), he also had to confess it to Amy. That makes Howard the third person to know about Sheldon's license.
On Howard's shelf, alongside the model rockets, are several model aircraft. They include, from left to right, NASA's SOFIA (Stratospheric Observatory for Infrared Astronomy) Boeing 747, a World War II US Army Air Forces C-47 with D-Day operational markings, a USAF T-38 trainer (a type of aircraft also used by NASA as a chase plane), and an AH-64 Apache attack helicopter.
In the season 6 episode The Parking Spot Escalation (2012), Howard gets a new car, which appears to be a gray Mini Countryman Crossover SUV. However, when Sheldon and Howard drive out to launch their rocket, he is driving a small Nissan. The car they are driving is actually Bernadette's, as she is seen driving it multiple times throughout the series.