When Mike is reading the postcard from Bobby (at 105:19), you see that their last name is Wright - as in the "Wright Brothers". Also, the envelope from Magic Spell, Inc., (at around 54 mins) is addressed to "Mike and Bobby Wright".
The film's original ending featured a present-day coda where a now-adult Mike, played by Tom Hanks, takes his children to the National Air and Space Museum, where the Radio Flyer/Plane hybrid is displayed next to the Wright Brothers' flying machine. Test audiences were confused by this ending and re-shoots led to the modern day prologue and epilogue seen in the final film.
Writer David Mickey Evans has stated that the script was much darker than the final film, and the child abuse angle was more prominent. When the film was taken over by Richard Donner, those elements were toned down. He also felt that the studio marketing "Radio Flyer" as a family film was a factor for the film's failure at the box-office.
The sacking of original director David Mickey Evans, replacing him with Richard Donner, and later re-shoots following test screenings meant that this modest little film's budget jumped from fifteen million dollars to thirty million dollars.
The original script ignited a bidding war in Hollywood and captured major media attention, as writer David Mickey Evans wrote the script while still in film school and eventually netted more than 1.25 million dollars, which included Evans services as screenwriter and director. When the studio thought their investment in the script too great to gamble on a first-time director, Evans was replaced by Richard Donner which sparked even more coverage, as Evans publicly distanced himself from the film which went on to be a major box-office and critical flop.
Writer David Mickey Evans later published the novella "The King of Pacoima" based on his original, record breaking script. The story reintegrated several discarded elements from the final film, including extended fantasy sequences with the buffalo. It also retained the original ending.
Elijah Wood and John Heard appeared with Macaulay Culkin in different films: Heard in Home Alone (1990), and Home Alone 2: Lost in New York (1992), and Wood in The Good Son (1993). Also, Thomas Ian Nicholas starred in Rookie of the Year (1993) with Daniel Stern, who played in the first two Home Alone movies as well.
The trivia items below may give away important plot points.
The film's ending with Bobby flying away in the makeshift airplane is the subject of fierce debate among audiences as to whether it should be taken figuratively, with Bobby dying from injuries sustained from falling off the cliff, or being killed by The King, and the whole "escape" scenario an imaginative way of Mike coping with his brother's loss, or if the ending should be taken literally, with Bobby actually traveling the world in the plane made from the wagon. Richard Donner, for his part, says the scene should be taken literally, though his declaration has not quieted the debate.
In the novella "The King of Pacoima," which David Mickey Evans based on his original screenplay, not the one used for the film, the names of his sons are revealed: Wilbur and Orville, another reference to the Wright Brothers. It also reveals that The King later died of alcoholism, and it's strongly implied that Bobby did die in his final flight. Mike imagines the flight as a way of rationalizing his own role in the accident which claimed his brother's life. In the final scene, an adult Mike takes his sons to see the Radio Flyer on display in the National Aerospace Museum, where it floats without any means of suspension. Mike then sees Bobby there, as an adult test pilot waiting to meet his nephews.